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() {
  int n, k;
  char s[50];

  scanf("%d %d\n", &n, &k);
  scanf("%s", s);

  if(s[k-1] == 'A') s[k-1] = 'a';
  if(s[k-1] == 'B') s[k-1] = 'b';
  if(s[k-1] == 'C') s[k-1] = 'c';

  printf("%s\n", s);

  return 0;
}