#include <bits/stdc++.h>
using namespace std;
int main() {
  std::ios_base::sync_with_stdio(0);
  int m, a;
  cin >> m >> a;
  string s;
  cin >> s;
  if (a == 0) return cout << s << "\n", 0;
  if (m == 1) return cout << 0 << "\n", 0;
  if (s[0] != '1') s[0] = '1', a--;
  for (int i = 1; i < m; i++) {
    if (a == 0) break;
    if (s[i] != '0') {
      s[i] = '0';
      a--;
    }
  }
  cout << s << "\n";
  return 0;
}
