func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MAXN = 2e5 + 10;   long long a[MAXN], dp[MAXN];   int main() {     long long n, ans = 0;     cin >> n;     for (int i = 0; i < n; i++) cin >> a[i];     for (int i = n - 2; i >= 0; i--) {       dp[i] = dp[i + 1];       if (a[i + 1] == 0) dp[i]++;     }     for (int i = 0; i < n; i++)       if (a[i] == 1) ans += dp[i];     cout << ans;   }   