#include <iostream>
using namespace std;
int main(){ int n; cin >> n; int a[100]; int s = 0; for(int i = 1; i <= n; i++) cin >> a[i]; for(int i = 1; i <= n; i++) { if(a[i] != 0) s+= a[i]; else if(a[i] == 0) { break; cout << s; } } cout << s; return 0;}