Determine The combination
Input: standard input
Output: standard output
Time Limit: 1 second

Jahir is a student of NSU ( Nice Students' University ). He hates the chapter Permutation & Combination of the subject Discrete Math. But his teacher give him a assignment to generate all the r combination of a string. But he is too busy with his new girlfriend to do the assignment himself. So he went to Shabuj, a student of CSE ( Calculation Science and Engineering ) in BUET ( Bangladesh University of Extraordinary Talents ). He asked him to make a program to generate the combinations. But Shabuj is always lazy. He wants your help.

Your task is to print all different r combinations of a string s (a r combination of a string s is a collection of exactly r letters from different positions in s).
There may be different permutations of the same combination; consider only the one that has its r characters in non-decreasing order.
The string consists of only lowercase letters. Any letter can occur more than once.

 Input

 

The input is consist of several test cases. Each test case consists of a string s ( the length of s is between 1 and  30 ) and an integer r ( 0 < r <= length of s ).

Output

 

For each test case you have to print all different r combinations of s in lexicographic order in separate line. You can assume there are at most 1000 different ones.
 

Sample Input

abcde 2
abcd 3
aba 2

Sample Output

ab
ac
ad
ae
bc
bd
be
cd
ce
de
abc
abd
acd
bcd
aa
ab

 

Problem setter: Hasan Shihab Uddin, CSE, BUET

Thanks to Adrian & Anupam for alternate solution and clarification.

"~~ No matter wherever you go, bad luck will follow you ~~"