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

int main() {
    int n;
    cin >> n;
    int a[25];
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    int x;
    cin >> x;
    int w = -1;
    // 从最后一个元素往前找
    for (int i = n; i >= 1; i--) {
        if (a[i] == x) {
            w = i;
            break; // 找到就立刻退出循环
        }
    }
    cout << w;
    return 0;
}