#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 69;
const long long LINF = 1e18;
void test() {}
int main() {
  cin.tie(0);
  cout.tie(0);
  ios_base::sync_with_stdio(false);
  long long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (n == 1) {
    if (k == 0)
      cout << s;
    else
      cout << 0;
    return 0;
  }
  if (k && s[0] != '1') {
    k--;
    s[0] = '1';
  }
  for (int i = 1; i < s.size() && k; i++) {
    if (s[i] != '0') s[i] = '0', k--;
  }
  cout << s;
}
