n = input()
k = int(input())
l = []
for i in n:
    if i!=' ':
        l.append(i)

for i in range(k):
    mx = 0
    for i in l:
        if int(i)>int(mx):
            mx = i
    l.remove(mx)

l.sort()
for i in l:
    print(i,end='')