#include <bits/stdc++.h>
using namespace std;
const int mod = 1000000007;
const int N = int(3e5) + 99;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  cerr.tie(nullptr);
  long long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (n == 1) {
    if (k > 0)
      cout << 0 << "\n";
    else
      cout << s << "\n";
    return 0;
  } else {
    for (long long i = 0; i < n; i++) {
      if (k == 0) break;
      if (i == 0) {
        if (s[i] != '1')
          s[i] = '1', k--;
        else
          continue;
      } else if (s[i] != '0')
        s[i] = '0', k--;
    }
  }
  cout << s << "\n";
  return 0;
}
