You have an array a with length n, you can perform operations. Each operation is like this: choose two adjacent elements from a, say x and y, and replace one of them with gcd(x, y), where gcd denotes the [greatest common divisor](https://en.wikipedia.org/wiki/Greatest_common_divisor).

What is the minimum number of operations you need to make all of the elements equal to 1?

Input

The first line of the input contains one integer n (1 ≤ n ≤ 2000) — the number of elements in the array.

The second line contains n space separated integers a1, a2, ..., an (1 ≤ ai ≤ 109) — the elements of the array.

Output

Print -1, if it is impossible to turn all numbers to 1. Otherwise, print the minimum number of operations needed to make all numbers equal to 1.

Examples

Input

5
2 2 3 4 6


Output

5


Input

4
2 4 6 8


Output

-1


Input

3
2 6 9


Output

4

Note

In the first sample you can turn all numbers to 1 using the following 5 moves:

  * [2, 2, 3, 4, 6]. 
  * [2, 1, 3, 4, 6]
  * [2, 1, 3, 1, 6]
  * [2, 1, 1, 1, 6]
  * [1, 1, 1, 1, 6]
  * [1, 1, 1, 1, 1]



We can prove that in this case it is not possible to make all numbers one using less than 5 moves.
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.math.BigInteger;


import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map.Entry;
import java.util.PriorityQueue;
import java.util.Random;
import java.util.TreeSet;


public final class CF_446_C{

	static boolean verb=true;
	static void log(Object X){if (verb) System.err.println(X);}
	static void log(Object[] X){if (verb) {for (Object U:X) System.err.print(U+" ");System.err.println("");}}
	static void log(int[] X){if (verb) {for (int U:X) System.err.print(U+" ");System.err.println("");}}
	static void log(long[] X){if (verb) {for (long U:X) System.err.print(U+" ");System.err.println("");}}

	static void logWln(Object X){if (verb) System.err.print(X);}
	static void info(Object o){	System.out.println(o);}
	static void output(Object o){outputWln(""+o+"\n");	}
	static void outputWln(Object o){try {out.write(""+ o);} catch (Exception e) {}}

	static int pgcd(int a,int b){
		if (a<b)
			return pgcd(b,a);
		while (b!=0){
			int c=b;
			b=a%b;
			a=c;
		}
		return a;
	}

	static long mod=1000000007;



	// Global vars
	static BufferedWriter out;
	static InputReader reader;

	static void process() throws Exception {


		out = new BufferedWriter(new OutputStreamWriter(System.out));
		reader=new InputReader(System.in);

		int n=reader.readInt();
		int[] a=new int[n];

		int p=0;
		int ok=0;
		for (int i=0;i<n;i++){
			a[i]=reader.readInt();
			p=pgcd(p,a[i]);
			if (a[i]==1)
				ok++;
		}
		int ans=-1;
		int[][] pp=new int[n][n];
		int best=n;
		if (p==1){
			loop: for (int len=0;len<n;len++){
				for (int i=0;i+len<n;i++){
					if (len==0){
						pp[i][len]=a[i];
					} else {
						pp[i][len]=pgcd(pp[i][len-1],a[i+len]);
					}
					if (pp[i][len]==1){
						best=len;
						break loop;
					}
				}
			}
			int op=Math.max(best-1, 0);
			//log("best:"+best);
			ans=op+(n-ok);
		
		}
		output(ans);
		try {
			out.close();
		}
		catch (Exception error){}


	}


	public static void main(String[] args) throws Exception {
		process();

	}

	static final class InputReader {
		private final InputStream stream;
		private final byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

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

		private int read() throws IOException {
			if (curChar >= numChars) {
				curChar = 0;
				numChars = stream.read(buf);
				if (numChars <= 0) {
					return -1;
				}
			}
			return buf[curChar++];
		}


		public final String readString() throws IOException {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			StringBuilder res=new StringBuilder();
			do {
				res.append((char)c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public final int readInt() throws IOException {
			int c = read();
			boolean neg=false;
			while (isSpaceChar(c)) {
				c = read();
			}
			char d=(char)c;
			//log("d:"+d);
			if (d=='-') {
				neg=true;
				c = read();
			}
			int res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			//log("res:"+res);
			if (neg)
				return -res;
			return res;

		}

		public final long readLong() throws IOException {
			int c = read();
			boolean neg=false;
			while (isSpaceChar(c)) {
				c = read();
			}
			char d=(char)c;
			//log("d:"+d);
			if (d=='-') {
				neg=true;
				c = read();
			}
			long res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			//log("res:"+res);
			if (neg)
				return -res;
			return res;

		}




		private boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}
	}


}