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 Python (3.4.3) (judge verdict: Wrong Answer)

# cook your dish here
# cook your dish here
import math
        
n,k=map(int,input().split())
summ=0
for i in range(1,n+1):
    if k/i<=1:
        value=0
    elif abs((math.log(k)-math.log(i))//math.log(2)-(math.log(k)-math.log(i))/math.log(2))<=0.00001:
        value = (math.log(k)-math.log(i))//math.log(2)
    else:
        value = (math.log(k)-math.log(i))//math.log(2)+1    
    po=(0.5)**value
    summ+=po
    
summ=summ/n
print(summ)