#include <bits/stdc++.h>
using namespace std;
string s;
int n, k;
class fastio {
 public:
  fastio() {
    ios_base::sync_with_stdio(false);
    cout.tie(nullptr);
    cin.tie(nullptr);
  }
} __fastio;
int main() {
  __fastio;
  cin >> n >> k >> s;
  if (n == 1) {
    if (k == 0)
      cout << s << endl;
    else
      puts("0");
    return 0;
  }
  if (k && s[0] != '1') s[0] = '1', k--;
  for (int i = 1; i < n; i++) {
    if (!k) break;
    if (s[i] != '0') {
      s[i] = '0';
      k--;
    }
  }
  cout << s;
  return 0;
}
