#include <bits/stdc++.h>
using namespace std;
int main() {
  long long t = 1;
  while (t--) {
    long long n, k;
    cin >> n >> k;
    string s, s2;
    cin >> s;
    if (n == 1) {
      if (k > 0)
        cout << 0;
      else
        cout << s;
      continue;
    }
    if (s[0] != '1' && k > 0) {
      s2 += '1';
      k--;
    } else {
      s2 += s[0];
    }
    for (long long i = 1; i <= k; i++) {
      if (i >= s.size()) break;
      s2 += '0';
      if (s[i] == '0') {
        k++;
      }
    }
    for (long long i = k + 1; i < s.size(); i++) {
      s2 += s[i];
    }
    cout << s2 << endl;
  }
  return 0;
}
