#include<bits/stdc++.h>
using namespace std;
int main(){
    int a[125],m,n,k=0;
    cin>>m;
    for(int i=0;i<m;i++){
     
        cin>>a[i];
    }
    cin>>n;
    for(int i=0;i<m;i++){
        if(a[i]==n){
            k=k+1;
            cout<<i+1;            
            break;
             
        }
         
    }
    if(k==0) cout<<"-1";
    return 0;
}
/**************************************************************
	Problem: 1154
	User: chenmingyu
	Language: C++
	Result: Accepted
	Time:22 ms
	Memory:2072 kb
****************************************************************/