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.
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.io.BufferedOutputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.InputMismatchException;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

public class Main {

	public static void main(String[] args) {
		if (args.length > 0 && args[0].toLowerCase().equals("local")) {
			try {
				System.setIn(new FileInputStream("input.txt"));
				System.setOut(new PrintStream(new File("output.txt")));
			} catch (IOException exc) {
			}
		}
		Task task = new Task();
		task.solve();
	}

	public static class Task {
		static final long MOD = (long) 1e9 + 7;
		static final PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));

		public void solve() {
			try {
				Scan sc = new Scan();
				int n = (int) sc.scanLong();
				Map<Integer, int[]> map = new HashMap<Integer, int[]>();
				int curr = -1;
				for (int i = 0; i < n; ++i) {
					curr = (int) sc.scanLong();
					if (map.containsKey(curr)) {
						int[] val = map.get(curr);
						if (val[1] == -1)
							continue;
						if (val[1] != 0 && val[0] + val[1] != i) {
							map.put(curr, new int[] { i, -1 });
						} else
							map.put(curr, new int[] { i, i - val[0] });
					} else {
						map.put(curr, new int[] { i, 0 });
					}
				}
				List<int[]> res = new ArrayList<>();
				for (Entry<Integer, int[]> entry : map.entrySet()) {
					if (entry.getValue()[1] == -1)
						continue;
					res.add(new int[] { entry.getKey(), entry.getValue()[1] });
				}

				Collections.sort(res, new Comparator<int[]>() {

					@Override
					public int compare(int[] a, int[] b) {
						return Integer.compare(a[0], b[0]);
					}

				});

				StringBuilder sb = new StringBuilder();
				sb.append(res.size()).append('\n');
				for (int[] pair : res) {
					sb.append(pair[0] + " " + pair[1]).append('\n');
				}
				out.println(sb);

			} finally {
				out.close();
			}
		}

		private void debug(Object... x) {
			StringBuilder sb = new StringBuilder();
			for (Object o : x)
				sb.append(String.valueOf(o)).append(" ");
			out.println(sb);
		}
	}

	public static class Scan {
		private byte[] buf = new byte[1024];
		private int index;
		private InputStream in;
		private int total;

		public Scan() {
			in = System.in;
		}

		public int scan() {
			if (total < 0)
				throw new InputMismatchException();
			if (index >= total) {
				index = 0;
				try {
					total = in.read(buf);
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
				if (total <= 0)
					return -1;
			}
			return buf[index++];
		}

		public long scanLong() {
			long integer = 0;
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			int neg = 1;
			if (n == '-') {
				neg = -1;
				n = scan();
			}
			while (!isWhiteSpace(n)) {
				if (n >= '0' && n <= '9') {
					integer *= 10;
					integer += n - '0';
					n = scan();
				} else
					throw new InputMismatchException();
			}
			return neg * integer;
		}

		public double scanDouble() {
			double doub = 0;
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			int neg = 1;
			if (n == '-') {
				neg = -1;
				n = scan();
			}
			while (!isWhiteSpace(n) && n != '.') {
				if (n >= '0' && n <= '9') {
					doub *= 10;
					doub += n - '0';
					n = scan();
				} else
					throw new InputMismatchException();
			}
			if (n == '.') {
				n = scan();
				double temp = 1;
				while (!isWhiteSpace(n)) {
					if (n >= '0' && n <= '9') {
						temp /= 10;
						doub += (n - '0') * temp;
						n = scan();
					} else
						throw new InputMismatchException();
				}
			}
			return doub * neg;
		}

		public String scanString() {
			StringBuilder sb = new StringBuilder();
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			while (!isWhiteSpace(n)) {
				sb.append((char) n);
				n = scan();
			}
			return sb.toString();
		}

		public char scanChar() {
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			return (char) n;
		}

		private boolean isWhiteSpace(int n) {
			if (n == ' ' || n == '\n' || n == '\r' || n == '\t' || n == -1)
				return true;
			return false;
		}
	}
}