#include <bits/stdc++.h>
using namespace std;
int main(){
	int m,n,a[110]={0},i,t=0;
	cin>>m;
	for(i=0;i<m;i++){
		cin>>a[i];
	
	}
	cin>>n;
	for(i=0;i<m;i++){
		if(n==a[i]){
			t=i+1;
			cout<<t;
			break;
		}
			
		
	}
	if(t==0){
		cout<<-1;
	}
}


/**************************************************************
	Problem: 1154
	User: fandaohan
	Language: C++
	Result: Accepted
	Time:19 ms
	Memory:2072 kb
****************************************************************/