#include <iostream>
using namespace std;
int main() {
    int m;
    cin>>m;
    int a[m];
    for(int i=0;i<m;i++){
    	cin>>a[i];
    	
    }
    int n;
    cin>>n;
    int f=0;
    for(int i=0;i<m;i++){
    	if(a[i]==n) {
    	f=1;
    	cout<<i+1;
    	break;
    	}
    }
	if(f==0) cout<<-1;
}
/**************************************************************
	Problem: 1154
	User: fandaohan
	Language: C++
	Result: Accepted
	Time:23 ms
	Memory:2072 kb
****************************************************************/