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

public class Main{
    public static BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
    public static PrintWriter stdOut = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    public static final int N = 100010;
    public static int n;
    public static int[] a = new int[N];
    public static Node[] tree = new Node[4 * N];
    public static int gcd(int a, int b) {
        return b == 0 ? a : gcd(b, a % b);
    }
    public static void built(int u, int l, int r) {
        if(l == r) tree[u] = new Node(l, r, a[l]);
        else {
            tree[u] = new Node(l, r, 0);
            int mid = (l + r) >> 1;
            built(u << 1, l, mid);
            built(u << 1 | 1, mid+1, r);
            tree[u].gcdValue = gcd(tree[u << 1].gcdValue, tree[u << 1 | 1].gcdValue);
        }
    }
    public static boolean check(int len) {
        for(int i = 1; i <= n - len + 1; i++) {
            int j = i + len - 1;
            if(query(1, i, j) == 1) return true;
        }
        return false;
    }
    public static int query(int u, int l, int r) {
        if(tree[u].l >= l && tree[u].r <= r) return tree[u].gcdValue;
        int gcdValue1 = 0; int gcdValue2 = 0;
        int mid = (tree[u].l + tree[u].r) >> 1;
        if(l <= mid) gcdValue1 = query(u << 1, l, r);
        if(r >= mid + 1) gcdValue2 = query(u << 1 | 1, l, r);
        if(gcdValue1 == 0 || gcdValue2 == 0) return Math.max(gcdValue1, gcdValue2);
        return gcd(gcdValue1, gcdValue2);
    }
    public static void main(String[] args) throws IOException{
        n = Integer.parseInt(stdIn.readLine());
        String[] sp = stdIn.readLine().split(" ");
        int numOf1 = 0;
        for(int i = 1; i <= n; i++) {
            a[i] = Integer.parseInt(sp[i-1]);
            if(a[i] == 1) numOf1++;
        }
        if(numOf1 != 0) {
            stdOut.println(n - numOf1); stdOut.flush();
            return;
        }
        built(1, 1, n);
        if(!check(n)) {
            stdOut.println("-1"); stdOut.flush();
            return;
        }
        int l = 1; int r = n;
        while(l < r) {
            int mid = (l + r) >> 1;
            if(check(mid)) r = mid;
            else l = mid + 1;
        }
        stdOut.println(l - 1 + n - 1);
        stdOut.flush();
    }
}

class Node{
    int l; int r; int gcdValue;
    public Node(int l, int r, int gcdValue) {
        this.l = l;
        this.r = r;
        this.gcdValue = gcdValue;
    }
}