#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  cin >> a >> b;
  string c;
  cin >> c;
  if (c.size() == 1 && b == 1) {
    cout << "0" << endl;
    return 0;
  }
  for (int i = 0; i < a; i++) {
    if (b == 0) {
      cout << c << endl;
      return 0;
    }
    if (i == 0 && c[i] != '1') {
      c[i] = '1';
      b--;
    }
    if (i != 0 && c[i] != '0') {
      c[i] = '0';
      b--;
    }
  }
  cout << c << endl;
}
