#include <bits/stdc++.h>
using namespace std;
const int mx = 1e5 + 10;
string s;
int n, m, j = 0;
int main() {
  cin >> n >> m;
  cin >> s;
  if (n == 1 && m > 0) {
    printf("0\n");
    return 0;
  } else {
    while (m) {
      if (j >= n) break;
      if (j == 0 && s[j] != '1') {
        s[j] = '1';
        m--;
      }
      if (j != 0 && s[j] != '0') {
        s[j] = '0';
        m--;
      }
      j++;
    }
    cout << s << endl;
  }
  return 0;
}
