#include <bits/stdc++.h>
using namespace std;
inline int64_t max(int64_t a, int64_t b) { return (a > b) ? a : b; }
inline int64_t min(int64_t a, int64_t b) { return (a < b) ? a : b; }
inline int64_t max3(int64_t a, int64_t b, int64_t c) {
  return max(a, max(b, c));
}
inline int64_t min3(int64_t a, int64_t b, int64_t c) {
  return min(a, min(b, c));
}
int64_t gcd(int64_t a, int64_t b) { return (a % b == 0) ? b : gcd(b, a % b); }
int64_t pow3(int64_t a, int64_t b, int64_t m = 1000000007) {
  int64_t res = 1;
  while (b > 0) {
    if (b & 1) res = (res * a) % m;
    a = (a * a) % m;
    b >>= 1;
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int q = 1;
  while (q--) {
    int n, k;
    cin >> n >> k;
    string s;
    cin >> s;
    if (n == 1 && k == 1)
      cout << "0";
    else {
      if (s[0] != '1' && k > 0) {
        s[0] = '1';
        k--;
      }
      for (int i = 1; i < n; i++) {
        if (k == 0)
          break;
        else if (s[i] != '0') {
          s[i] = '0';
          k--;
        }
      }
      cout << s;
    }
  }
  return 0;
}
