#include <bits/stdc++.h>   using namespace std;   int MinDist(int n, int k, const string& s) {     int first_cow_pos = 0;     while (first_cow_pos < n && s[first_cow_pos] ==  1 ) {       ++first_cow_pos;     }     int last_cow_pos = first_cow_pos;     int rooms = 1;     while (rooms < k + 1) {       ++last_cow_pos;       if (s[last_cow_pos] ==  0 ) {         ++rooms;       }     }     int farmer_pos = first_cow_pos;     int delta = last_cow_pos - first_cow_pos;     for (int i = first_cow_pos + 1; i <= last_cow_pos; ++i) {       if (s[i] ==  0  && i - first_cow_pos < delta && last_cow_pos - i < delta) {         delta = max(i - first_cow_pos, last_cow_pos - i);         farmer_pos = i;       }     }     --rooms;     for (++first_cow_pos; first_cow_pos < n; ++first_cow_pos) {       if (s[first_cow_pos] ==  1 ) {         continue;       }       while (rooms < k + 1 && last_cow_pos < n) {         ++last_cow_pos;         if (last_cow_pos == n) {           break;         }         if (s[last_cow_pos] ==  0 ) {           ++rooms;         }       }       if (last_cow_pos == n) {         break;       }       int npos = max(farmer_pos, first_cow_pos);       int cur_delta = max(farmer_pos - first_cow_pos, last_cow_pos - farmer_pos);       while (npos < last_cow_pos) {         ++npos;         if (s[npos] ==  1 ) {           continue;         }         if (npos - first_cow_pos < cur_delta && last_cow_pos - npos < cur_delta) {           cur_delta = max(npos - first_cow_pos, last_cow_pos - npos);           farmer_pos = npos;         } else if (npos - first_cow_pos >= cur_delta) {           break;         }       }       delta = min(delta, cur_delta);       --rooms;     }     return delta;   }   int MinDistSlow(int n, int k, const string& s) {     int result = n;     for (int fcp = 0; fcp < n; ++fcp) {       if (s[fcp] ==  1 ) {         continue;       }       int lcp = fcp;       int rooms = 1;       while (rooms < k + 1 && lcp < n) {         ++lcp;         if (lcp == n) {           break;         }         if (s[lcp] ==  0 ) {           ++rooms;         }       }       if (lcp == n) {         break;       }       for (int fp = fcp; fp <= lcp; ++fp) {         if (s[fp] ==  1 ) {           continue;         }         int delta = max(fp - fcp, lcp - fp);         if (delta < result) {           result = delta;         }       }     }     return result;   }   int main() {     int n, k;     cin >> n >> k;     string s;     char buffer[1000000];     scanf( %s , buffer);     s = buffer;     int delta = MinDist(n, k, s);     cout << delta << endl;     return 0;   }   