PROGRAMMING:The problem of alphabet arrangement
How many permutations are there in a row of $$n (0 < n / Leq m) $$letters selected from the $$m (0 < m / Leq 26) $$capital letters?
Please write a program, input $$M $$and $$n $$and output all permutations of any $$n $$letters in the continuous $$M $$letters starting from a.
Requirements: output a permutation for each line, output in dictionary order.
####Input sample
```in
3 2
```
####Output sample
```out
AB
AC
BA
BC
CA
CB
```
answer：If there is no answer, please comment
Please write a program, input $$M $$and $$n $$and output all permutations of any $$n $$letters in the continuous $$M $$letters starting from a.
Requirements: output a permutation for each line, output in dictionary order.
####Input sample
```in
3 2
```
####Output sample
```out
AB
AC
BA
BC
CA
CB
```
answer：If there is no answer, please comment