#include<bits/stdc++.h>
using namespace std;
int n,m,a[20];
int main(){
    while(scanf("%d",&n)!=EOF){
        for(int i=0;i<n;i++) cin>>a[i];
        cin>>m;
        bool b=false;
        for(int i=0;i<n;i++){
            if(a[i]==m){
                cout<<i<<endl,b=true;
                break;
            }
        }
        if(!b) cout<<"No"<<endl;
    }
    return 0;
}