#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e18;
const long double inf = 1e18;
const long long MOD = (long long)(1e9 + 7);
const double EPS = 1e-6;
void file_io(string inp = "input.txt", string out = "output.txt",
             bool debug = false) {
  freopen(inp.c_str(), "r", stdin);
  if (!debug) freopen(out.c_str(), "w", stdout);
}
void fast_io() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
}
int32_t main() {
  long long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (n == 1) {
    cout << (k > 0 ? "0" : s) << "\n";
    return 0;
  }
  for (long long i = 0; i < n; ++i) {
    if (k > 0) {
      if (i == 0) {
        if (s[i] == '1') continue;
        s[i] = '1';
        k--;
      } else {
        if (s[i] == '0') continue;
        s[i] = '0';
        k--;
      }
    }
  }
  cout << s << "\n";
  return 0;
}
