#include <bits/stdc++.h>
using namespace std;
const int N = 10;
vector<int> mod = {1000000009 , 1000000007 , 998244353} ;
const int P = 1e9;
int n ;
string a[100005];
bool ok[100005];
int t[100005];
int fpow(int a,int b,int mod) {
    int ans = 1;
    while(b) {
        if(b & 1) ans = 1LL * ans * a %mod;
        a = 1LL * a * a % mod ; b >>= 1;
    }
    return ans;
}
bool check(int x) {
    for(int i = 2;i * i <= x;i++) {
        if(x % i == 0) return 0;
    }
    return 1;
}
mt19937 rnd(0);
int main() {
    ios::sync_with_stdio(false) ; cin.tie(0);
    cin >> n;
    for(int i = 1;i <= n;i++) {
        cin >> a[i] ; ok[i] = 1;
    }
    for(int i = 4 ; i <= N ;i++ ) {
        int d = rnd()%P + 1;
        while(!check(d)) d = rnd()%P + 1;
        mod.push_back(d);
    }
    for(int p = 0;p < N;p++) {
        int prod = 1;

        for(int i = 1;i <= n;i++) {
            int s = 0;
            for(int j = 0;j < a[i].size();j++) s = (s * 10LL + a[i][j] - '0') % mod[p] ;
            prod = 1LL * prod * s % mod[p];
            t[i] = fpow(s , n , mod[p]) ;
        }
        for(int i = 1;i <= n;i++) {
            if(t[i] != prod) ok[i] = 0;
        }
    }
    for(int i = 1;i <= n;i++) {
        if(ok[i]){
            cout << i << '\n' ; return 0;
        }
    }
}