N, K = map(int, input().split())
S = list(input())
S = list(map(int, S))
ans = [[], [], []]
ans[0] = S
for i in range(2):
    for j in range(len(ans[i]) - 1):
        ans[i + 1].append(1 - (ans[i][j]&ans[i][j+1]))

N -= K + 1
if N % 2 == 0:
    d = N // 2
    print(*ans[1][d:len(ans[1])-d], sep="")
else:
    d = N // 2
    print(*ans[2][d:len(ans[2])-d], sep="")