#include<bits/stdc++.h>
using namespace std;
int main(){
	int a[101]={0},m,n,i,z=0;
	cin>>m;
	for(i=0;i<m;i++){
		cin>>a[i];
	}
	cin>>n;
	for(i=0;i<m;i++){
		if(a[i]==n){
			z=1;
			cout<<i+1;
			break;	
		}
	}
	if(z==0){
		cout<<"-1";
	}
	return 0;
}

/**************************************************************
	Problem: 1154
	User: zouliangyin
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:2072 kb
****************************************************************/