#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, k, i, j;
  cin >> n >> k;
  string s;
  cin >> s;
  if (k == 0) {
    cout << s << endl;
    return 0;
  } else if (n == 1) {
    cout << "0" << endl;
    return 0;
  } else if (s[0] == '1') {
    for (i = 1; i < n; ++i) {
      if (s[i] != '0') {
        s[i] = '0';
        k--;
        if (k == 0) {
          break;
        }
      }
    }
  } else if (s[0] != '1') {
    s[0] = '1';
    for (j = 1; j < n; j++) {
      if (s[j] != '0') {
        if (k == 1) {
          break;
        }
        s[j] = '0';
        k--;
      }
    }
  }
  cout << s << endl;
  return 0;
}
