import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }




void main() {
  try {
    for (; ; ) {
      const N = readInt;
      const K = readInt;
      const S = readToken;
      
      int n = N;
      auto cs = S.dup;
      if ((n - K) % 2 != 0) {
        auto ccs = new char[n - 1];
        foreach (i; 0 .. n - 1) {
          ccs[i] = (cs[i] == '1' && cs[i + 1] == '1') ? '0' : '1';
        }
        --n;
        cs = ccs;
      }
      debug {
        writeln("n = ", n);
        writeln("cs = ", cs);
      }
      
      auto ans = new char[K];
      ans[] = '0';
      for (int i = 0, j; i < n; i = j) {
        for (j = i; j < n && cs[i] == cs[j]; ++j) {}
        if (cs[i] == '1' && (n - K == 0 || j - i >= 2)) {
          const l = max(i - (n - K) / 2, 0);
          const r = min(j - (n - K) / 2, K);
          if (l < r) {
            ans[l .. r] = '1';
          }
        }
      }
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}