pc20_zadB

#include <iostream>
#include <string>
#include <string.h>

//#include <limits>
//#include <algorithm>
//#include <math.h>
//#include <bitset> // bitset< 32 >( num ).to_string();
#define ll long long

#define print(var) cout << #var << ": " << var << endl;
#define println(var); cout << var << endl;

using namespace std;


int main() {
    ios_base::sync_with_stdio(false);

    int a;
    while (cin >> a && a != 0) {
        int* m = new int[a];
        //print(a);

        bool sameNum = true;

        for (int i = 0; i < a; i++) {
            cin >> m[i];
            if (i > 0) {
                if (m[i] != m[i - 1]) {
                    sameNum = false;
                }
            }
        }
        //print(sameNum);
        if (sameNum) {
            cout << sameNum << endl;
        }
        else {
            int n = 2;

            //print(n);

            sameNum = true;
            int lastPass = 0;

            while (n <= a / 2) {
                int lastN;
                //print(n);
                for (int j = 0; j < n; j++) {
                    for (int i = j; i < a; i += n) {
                        if (i > j) {
                            if (lastN != m[i]) {
                                //print(m[i]);
                                i = a;
                                j = a;
                            }
                        }
                        lastN = m[i];
                    }

                    if (j == n - 1) {
                        if (lastPass == 0) {
                            lastPass = j + 1;
                            n = a;
                        }
                    }
                }

                n++;
            }

            cout << lastPass << endl;
        }
    }
}