#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  long long int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (n == 1) {
    if (k == 0)
      cout << s;
    else
      cout << 0;
  } else {
    for (int i = 0; i < s.length(); i++) {
      if (k > 0) {
        if (i == 0) {
          if (s[i] != '1') {
            s[i] = '1';
            --k;
          } else
            continue;
        } else {
          if (s[i] != '0') {
            s[i] = '0';
            --k;
          } else
            continue;
        }
      } else
        break;
    }
    cout << s;
  }
  return 0;
}
