func_code_string: #include <bits/stdc++.h>   using namespace std;   long long front[1000001], back[1000001], vt[1000001];   int main() {     long long k, sz, ko = 0, j = 0, kq = 0;     string s;     cin >> k >> s;     sz = s.size();     s =     + s;     for (long long i = 1; i <= sz + 1; i++) {       front[i] = ko;       if (s[i] ==  0 )         ko++;       else         ko = 0;     }     ko = 0;     for (long long i = sz; i >= 1; i--) {       back[i] = ko;       if (s[i] ==  0 )         ko++;       else         ko = 0;     }     for (long long i = 1; i <= sz; i++)       if (s[i] ==  1 ) j++, vt[j] = i;     if (k == 0) {       vt[j + 1] = sz + 1;       front[sz + 1] = ((s[sz] ==  1 ) ? 0 : front[sz] + 1);       j++;       for (long long i = 1; i <= j; i++)         kq += front[vt[i]] * (front[vt[i]] + 1) / 2;       cout << kq;       return 0;     }     for (long long i = 1; i <= j - k + 1; i++)       kq += (front[vt[i]] + 1) * (back[vt[i + k - 1]] + 1);     cout << kq;   }   