func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 1e6 + 1;   int a[N];   int main() {     long long ans = 0, ones = 0, k;     string s;     cin >> k >> s;     a[0] = -1;     for (int i = 0; i < s.size(); i++) {       if (s[i] ==  1 ) ones++, a[ones] = i;       if (ones >= k) {         if (k != 0)           ans += a[ones - k + 1] - a[ones - k];         else if (s[i] ==  0 )           ans += i - a[ones];       }     }     cout << ans << endl;   }   