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 (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>

int main(void) {
	int i;

	i = 'A' - 'a';
	
	int N;

	scanf("%d", &N);

	int K;

	scanf("%d", &K);

	char S[N];

	scanf("%s", S);
	
	S[K - 1] -= i;
	
	printf("%s", S);

	return 0;
}