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)

int main(void)
{
	int n, k;
	char s[51];

    scanf("%d %d", &n, &k);
	scanf("%s", s);
	s[n] = '\0';
	s[k-1] = s[k-1] -  'A' + 'a';

	printf("%s \n", s);
	return 0;
}