#include <bits/stdc++.h>
using namespace std;
const long long int mod = 1e9 + 7;
const int sz = 1e4 + 50, mxn = 1e6 + 10;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (k == 0) {
    cout << s << endl;
    return 0;
  }
  if (n == k && k == 1) {
    cout << 0 << endl;
    return 0;
  }
  for (int i = 0; i < n; i++) {
    if (i == 0 && s[i] == '1')
      cout << s[i];
    else if (i == 0 && s[i] != '1') {
      cout << "1";
      k--;
    } else if (s[i] == '0')
      cout << "0";
    else if ((s[i] >= '1' && s[i] <= '9') && k > 0) {
      cout << "0";
      k--;
    } else
      cout << s[i];
  }
  return 0;
}
