Problem:
Score : 100 points

Problem Statement

You are given a string S of length N consisting of A, B and C, and an integer K which is between 1 and N (inclusive).
Print the string S after lowercasing the K-th character in it.

Constraints

1 ≤ N ≤ 50

1 ≤ K ≤ N

S is a string of length N consisting of A, B and C.

Input

Input is given from Standard Input in the following format:

N K
S

Output

Print the string S after lowercasing the K-th character in it.

Sample Input 1

3 1
ABC

Sample Output 1

aBC

Sample Input 2

4 3
CABA

Sample Output 2

CAbA

Solution in Fortran (gfortran v4.8.4) (judge verdict: Accepted)

program aaa
implicit none

integer :: n, k, i
character(50) :: s

read*, n, k
read*, s

s=trim(s)
i=iachar(s(k:k))+32
s(k:k)=achar(i)
  
write(*,'(a)') s

end program