#include <iostream>
using namespace std;

int main() {
    int m, n;
    cin >> m;
    
    if (m == 0) {
        cout << -1;
        return 0;
    }
    
    int arr[100];
    for (int i = 0; i < m; i++) {
        cin >> arr[i];
    }
    
    cin >> n;
    
    int position = -1;
    for (int i = 0; i < m; i++) {
        if (arr[i] == n) {
            position = i + 1; // 题目要求输出位置从1开始
            break;
        }
    }
    
    cout << position;
    return 0;
}
/**************************************************************
	Problem: 1154
	User: fandaohan
	Language: C++
	Result: Accepted
	Time:16 ms
	Memory:2072 kb
****************************************************************/