#include <iostream>
using namespace std;
int main()
{
    int n, a[10000], x, i;
    cin >> n;
    for (i=0; i<n; i++) cin >> a[i];
    cin >> x;
    for (i=0; i<n; i++){
        if (a[i] == x){
            cout << i+1 << endl;
            return 0;
        }
    }
    cout << "-1" << endl;
    return 0;
}