#include <iostream>
using namespace std;

int main(){
	int n,a,yuki;
	int sum =0;
	cin >> n;
	for(int i=0;i<n;i++){
		cin >> a;
		sum +=a;
	}
	cin >> yuki;
	if(sum != yuki) cout << sum -yuki << "\n";
	else cout << yuki << "\n";
}