Number – X Largest Digits Ascending

Number – X Largest Digits Ascending: Accept a number N and print the first X largest digits in N in ascending order.

Input Format:
The first line contains N and X separated by a space.

Output Format:
The first line contains the X largest digits in N in ascending order.

Boundary Conditions:
1 <= N <= 999999999999999
1 <= X <= 10

Example Input/Output 1:
Input:
1684285215
3

Output:
568

Example Input/Output 2:
Input:
90217623
2

Output:
79

n=input().strip()
m=int(input())
l=[]
t=list(sorted(set(n)))
for i in range(m):
    l.append(t[::-1][i])
print(*l[::-1],sep="")