One day Jeff got hold of an integer sequence a1, a2, ..., an of length n. The boy immediately decided to analyze the sequence. For that, he needs to find all values of x, for which these conditions hold:

  * x occurs in sequence a. 
  * Consider all positions of numbers x in the sequence a (such i, that ai = x). These numbers, sorted in the increasing order, must form an arithmetic progression. 



Help Jeff, find all x that meet the problem conditions.

Input

The first line contains integer n (1 ≤ n ≤ 105). The next line contains integers a1, a2, ..., an (1 ≤ ai ≤ 105). The numbers are separated by spaces.

Output

In the first line print integer t — the number of valid x. On each of the next t lines print two integers x and px, where x is current suitable value, px is the common difference between numbers in the progression (if x occurs exactly once in the sequence, px must equal 0). Print the pairs in the order of increasing x.

Examples

Input

1
2


Output

1
2 0


Input

8
1 2 1 3 1 2 1 5


Output

4
1 2
2 4
3 0
5 0

Note

In the first test 2 occurs exactly once in the sequence, ergo p2 = 0.
//package CodeForces;

/*In the name of Allah the Most Merciful.
 * Author
 * Md. Toufiqul Islam
 * Dept. Of CSE
 * Ahsanullah University Of Science And Technology
*/

import java.io.*;
import java.util.*;
import java.math.*;

public class R204B {
    public static void main(String[] args) {
        InputReader sc = new InputReader(System.in);
        OutputWriter out = new OutputWriter(System.out);

        int n = sc.nextInt();

        List<Integer> list[] = new ArrayList[100000+1];

        for(int i=1;i<=100000;i++){
            list[i] = new ArrayList<>();
        }
        TreeSet<Integer> set = new TreeSet<>();

        for(int i=0;i<n;i++){
            int a = sc.nextInt();

            if(set.contains(a)){
                list[a].add(i);
            }
            else{
                set.add(a);
                list[a].add(i);
            }
        }

        Iterator<Integer> it = set.iterator();
        List<String> ans = new ArrayList<>();

        while (it.hasNext()){
            int a = it.next();

            if(list[a].size()==1){

                ans.add(Integer.toString(a)+" 0");
            }
            else if(list[a].size()==2){
                int diff = Math.abs(list[a].get(0)-list[a].get(1));

                ans.add(Integer.toString(a)+" "+Integer.toString(diff));
            }
            else{

                int diff = Math.abs(list[a].get(0)-list[a].get(1));

                boolean isSame = true;

                for(int i=2;i<list[a].size();i++){
                   int temp =  Math.abs(list[a].get(i)-list[a].get(i-1));
                  if(diff!=temp){
                      isSame = false;
                      break;
                  }
                }

                if(isSame){
                    ans.add(Integer.toString(a)+" "+diff);
                }
            }


        }

        out.println(ans.size());

        if(ans.size()>0){
            for (String s: ans){
                out.println(s);
            }
        }



        out.close();
    }

    public static class InputReader {
        private boolean finished = false;

        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public int peek() {
            if (numChars == -1) {
                return -1;
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    return -1;
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar];
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public String nextString() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                if (Character.isValidCodePoint(c)) {
                    res.appendCodePoint(c);
                }
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }

        public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        private String readLine0() {
            StringBuilder buf = new StringBuilder();
            int c = read();
            while (c != '\n' && c != -1) {
                if (c != '\r') {
                    buf.appendCodePoint(c);
                }
                c = read();
            }
            return buf.toString();
        }

        public String readLine() {
            String s = readLine0();
            while (s.trim().length() == 0) {
                s = readLine0();
            }
            return s;
        }

        public String readLine(boolean ignoreEmptyLines) {
            if (ignoreEmptyLines) {
                return readLine();
            } else {
                return readLine0();
            }
        }

        public BigInteger readBigInteger() {
            try {
                return new BigInteger(nextString());
            } catch (NumberFormatException e) {
                throw new InputMismatchException();
            }
        }

        public char nextCharacter() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            return (char) c;
        }

        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E') {
                    return res * Math.pow(10, nextInt());
                }
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E') {
                        return res * Math.pow(10, nextInt());
                    }
                    if (c < '0' || c > '9') {
                        throw new InputMismatchException();
                    }
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

        public boolean isExhausted() {
            int value;
            while (isSpaceChar(value = peek()) && value != -1) {
                read();
            }
            return value == -1;
        }

        public String next() {
            return nextString();
        }

        public SpaceCharFilter getFilter() {
            return filter;
        }

        public void setFilter(SpaceCharFilter filter) {
            this.filter = filter;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }

        public int[] nextIntArray(int n) {
            int[] array = new int[n];
            for (int i = 0; i < n; ++i) array[i] = nextInt();
            return array;
        }

        public int[] nextSortedIntArray(int n) {
            int array[] = nextIntArray(n);
            Arrays.sort(array);
            return array;
        }

        public int[] nextSumIntArray(int n) {
            int[] array = new int[n];
            array[0] = nextInt();
            for (int i = 1; i < n; ++i) array[i] = array[i - 1] + nextInt();
            return array;
        }

        public long[] nextLongArray(int n) {
            long[] array = new long[n];
            for (int i = 0; i < n; ++i) array[i] = nextLong();
            return array;
        }

        public long[] nextSumLongArray(int n) {
            long[] array = new long[n];
            array[0] = nextInt();
            for (int i = 1; i < n; ++i) array[i] = array[i - 1] + nextInt();
            return array;
        }

        public long[] nextSortedLongArray(int n) {
            long array[] = nextLongArray(n);
            Arrays.sort(array);
            return array;
        }
    }

    public static class OutputWriter {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }

        public void print(char[] array) {
            writer.print(array);
        }

        public void print(Object... objects) {
            for (int i = 0; i < objects.length; i++) {
                if (i != 0) {
                    writer.print(' ');
                }
                writer.print(objects[i]);
            }
        }

        public void print(int[] array) {
            for (int i = 0; i < array.length; i++) {
                if (i != 0) {
                    writer.print(' ');
                }
                writer.print(array[i]);
            }
        }

        public void print(double[] array) {
            for (int i = 0; i < array.length; i++) {
                if (i != 0) {
                    writer.print(' ');
                }
                writer.print(array[i]);
            }
        }

        public void print(long[] array) {
            for (int i = 0; i < array.length; i++) {
                if (i != 0) {
                    writer.print(' ');
                }
                writer.print(array[i]);
            }
        }

        public void println(int[] array) {
            print(array);
            writer.println();
        }

        public void println(double[] array) {
            print(array);
            writer.println();
        }

        public void println(long[] array) {
            print(array);
            writer.println();
        }

        public void println() {
            writer.println();
        }

        public void println(Object... objects) {
            print(objects);
            writer.println();
        }

        public void print(char i) {
            writer.print(i);
        }

        public void println(char i) {
            writer.println(i);
        }

        public void println(char[] array) {
            writer.println(array);
        }

        public void printf(String format, Object... objects) {
            writer.printf(format, objects);
        }

        public void close() {
            writer.close();
        }

        public void flush() {
            writer.flush();
        }

        public void print(long i) {
            writer.print(i);
        }

        public void println(long i) {
            writer.println(i);
        }

        public void print(int i) {
            writer.print(i);
        }

        public void println(int i) {
            writer.println(i);
        }

        public void separateLines(int[] array) {
            for (int i : array) {
                println(i);
            }
        }
    }

}
