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 C (Clang 3.8.0) (judge verdict: Accepted)

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int main()
{
	int k, n;
	char s[52];
	scanf("%d%d", &n, &k);
	scanf("%s", s);
	if (s[k - 1] >= 'a'&&s[k - 1] <= 'c')s[k - 1] = s[k - 1] - 32;
	if(s[k - 1] >= 'A'&&s[k - 1] <= 'C')s[k - 1] = s[k - 1] + 32;
	printf("%s\n", s);
	return 0;
}