#include <bits/stdc++.h>
using namespace std;
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cerr << name << " : " << arg1 << "\n";
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << " : " << arg1 << " , ";
  __f(comma + 1, args...);
}
inline long long int gcd(long long int a, long long int b) {
  a = abs(a), b = abs(b);
  while (b) a = a % b, swap(a, b);
  return a;
}
inline long long int power(long long int a, long long int p) {
  long long int res = 1, x = a;
  while (p) {
    if (p & 1) res = (res * x);
    x = (x * x), p >>= 1;
  }
  return res;
}
inline long long int big_mod(long long int a, long long int p,
                             long long int m) {
  long long int res = 1 % m, x = a % m;
  while (p) {
    if (p & 1) res = (res * x) % m;
    x = (x * x) % m, p >>= 1;
  }
  return res;
}
const int INF = 1e9;
int main() {
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (k == 0) {
    return cout << s << endl, 0;
  } else if (k == 1 && n == 1) {
    return cout << "0" << endl, 0;
  }
  string ans = "";
  for (int i = 0; i < min(n, k); i++) {
    if (i == 0) {
      if (s[i] == '1') {
        k++;
      }
      ans += "1";
    } else {
      if (s[i] == '0') {
        k++;
      }
      ans += "0";
    }
  }
  if (n > k) {
    for (int i = k; i < n; i++) {
      ans.push_back(s[i]);
    }
  }
  cout << ans << endl;
  return 0;
}
