#include <bits/stdc++.h>
using namespace std;

int main() {
    int n = 0;
    while (scanf("%d", &n) != EOF) {
        int arr[200];
        int x = 0, j = 0, xiabiao = -1;
        for (int i = 0; i < n; i++) {
            scanf("%d", &arr[i]);
        }

        scanf("%d", &x);
        for (j = 0; j < n; ++j) {
            if (arr[j] == x) {
                xiabiao = j;
                break;

            }//查到了记得break
        }
        cout << xiabiao << endl;
    }
    return 0;
}