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 Ruby (2.3.3) (judge verdict: Runtime Error)

S = gets.chomp

first = S[0..1].to_i
second = S[2..3].to_i

ft = false
ft = true if (1 <= first  || first <= 12)

st = false
st = true if (1 <= second  || second <= 12)

return 'AMBIGUOUS' if (ft && st)
return 'NA' if (!ft && !st)
return 'MMYY' if ft
return 'YYMM'