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: Wrong Answer)

program main
implicit none
integer :: n, k, i
character :: s*50,t*50

read(*,*) n, k
read(*,*) s(1:n)
do i = 1, n
   if( i/= k ) then
   t(i:i) = s(i:i)
   else
   t(i:i) = char( ichar(s(i:i))+32 )
   end if
end do
write(*,*) t

end program main