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



	return 0;
}

/**************************************************************
	Problem: 1154
	User: hbq
	Language: C++
	Result: Accepted
	Time:13 ms
	Memory:2072 kb
****************************************************************/