/* -*- coding: utf-8 -*-
 *
 * 2037.cc:  No.2037 NAND Pyramid - yukicoder
 */

#include<cstdio>
#include<algorithm>
 
using namespace std;

/* constant */

const int MAX_N = 400000;

/* typedef */

/* global variables */

char ss[2][MAX_N + 4];

/* subroutines */

void reduce(int n, char s0[], char s1[]) {
  for (int i = 0; i + 1 < n; i++)
    s1[i] = (s0[i] == '1' && s0[i + 1] == '1') ? '0' : '1';
  s1[n - 1] = '\0';
}

/* main */

int main() {
  int n, k;
  scanf("%d%d%s", &n, &k, ss[0]);

  int cur = 0, nxt = 1;
  reduce(n, ss[cur], ss[nxt]);
  swap(cur, nxt), n--;
  //puts(ss[cur]);

  if ((k ^ n) & 1) {
    reduce(n, ss[cur], ss[nxt]);
    swap(cur, nxt), n--;
  }

  int d = (n - k) / 2;
  for (int i = 0; i < k; i++) putchar(ss[cur][i + d]);
  putchar('\n');
  return 0;
}