#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vector<int>>;
using pii = pair<int, int>;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define repr(i, n) for (int i = (int)(n - 1); i >= 0; --i)

int main() {
    int n, K;
    string s;
    cin >> n >> K >> s;
    vi r(n);
    rep(i, n) r[i] = s[i] - '0';
    rep(i, n - 1) r[i] = 1 - (r[i] & r[i + 1]);
    if ((n - K) & 1) {
        int d = (n - K - 1) / 2;
        rep(k, K) cout << r[k + d];
        cout << endl;
    } else {
        rep(i, n - 2) r[i] = 1 - (r[i] & r[i + 1]);
        int d = (n - K - 2) / 2;
        rep(k, K) cout << r[k + d];
        cout << endl;
    }
    return 0;
}