include <bits/stdc++.h>
using namespace std;
int main()
{
    int n,h,t=-1;
    cin>>n;
    int m[100];
    for(int i=0;i<n;i++){
        cin>>m[i];
    }
    cin>>h;
    for(int i=0 ; i<n ; i++){
        if(m[i]==h){
            t=i+1;
            break;
        }
    }
     
    cout<<t<<endl;
return 0;
 
}
/**************************************************************
	Problem: 1154
	User: lijinkai
	Language: C++
	Result: Compile Error
****************************************************************/