402. Remove K digits

num = [int(i) for i in input()]
k = int(input())

ans = []
pre = 0
for i in range(k, len(num)):
  minVal = min(num[pre:i+1])
  ans.append(minVal)
  pre = num[pre:i+1].index(minVal)+pre+1

i = 0
while(i < len(ans) and ans[i] == 0):
  i+=1
if i == len(ans):
  i = 0
  ans = [0]
print(''.join([str(i) for i in ans[i:]]))