#include <bits/stdc++.h>
using namespace std;

int main() {
    int N,K;
    string S;
    cin >> N >> K >> S;
    int diff = (N-K)/2;
    string ans = string(K,'1');
    if(K%2 == N%2) {
        ans = string(K,'0');
    }
    for(int i = 0; i < K; i++) {
        if(K%2 == N%2) {
            if(S[i+diff] == '1' && S[i+diff+1] == '1') {
                ans[i] = '1';
                if(i+1 < K) ans[i+1] = '1';
            }
        }
        else {
            if(S[i+diff] == '1' && S[i+diff+1] == '1') {
                ans[i] = '0';
            }
        }
    }
    cout << ans << endl;
}