#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:16000000")
using namespace std;
long long mod = 998244353;
long double inf = 1e9;
long double eps = 1e-8;
long double pi = acos(-1);
ifstream in("input.txt");
ofstream out("output.txt");
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (k == 0) {
    cout << s;
  } else {
    if (s.size() == 1) {
      cout << 0;
      return 0;
    }
    if (s[0] != '1') {
      s[0] = '1';
      k--;
    }
    for (int i = 1; i < n; i++) {
      if (k == 0) break;
      if (s[i] != '0') {
        s[i] = '0';
        k--;
      }
    }
    cout << s;
  }
  return 0;
}
