#include<iostream>
using namespace std;
int n,a[9937],qwq;
int main(){
	bool flag=false;
	cin>>n;
	for(int i=0;i<n;i++) cin>>a[i];
	cin>>qwq;
	for(int i=0;i<n;i++){
		if(a[i]==qwq){
			cout<<i<<endl;
			flag=true;
			break;
		}
	}
	if(flag==false) cout<<-1<<endl;
	return 0;
}

https://www.luogu.com.cn/record/77927607