// PR Bab 07, soal 3 -- pembahasan.

#include <iostream>
using namespace std;

const int MAKS = 100005;
int a[MAKS];

int main() {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) cin >> a[i];

    int target;
    cin >> target;

    int posisi = -1;
    for (int i = 0; i < n; i++) {
        if (a[i] == target) { posisi = i; break; }
    }

    cout << posisi << "\n";
    return 0;
}