문제
풀이
#include <iostream>
using namespace std;
void solve(void) {
int n; cin >> n;
long long ans = 0, cur = 0;
while (n--) {
int x; cin >> x;
cur += x == 1 ? 1 : -1;
ans += cur;
}
cout << ans;
}
int main(void) {
ios::sync_with_stdio(false);
cin.tie(nullptr);
solve();
return 0;
}