#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: jiangyuanfeng
	Language: C++
	Result: Compile Error
****************************************************************/