#include <iostream>
using namespace std;
 
int main() {
    int a[100] = {0}; 
    int n, i, b;
    cin >> n; 
    for (i = 0; i < n; i++) {
        cin >> a[i];
    }
    cin >> b;
    bool found = false;  
    for (i = 0; i < n; i++) {
        if (a[i] == b) {
            cout << i + 1; 
            found = true;  
            break; 
        }
    }
    if (!found) {
        cout << -1; 
    }
    return 0;
}    
/**************************************************************
	Problem: 1154
	User: lihean
	Language: C++
	Result: Accepted
	Time:16 ms
	Memory:2072 kb
****************************************************************/