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