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