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: Runtime Error)

#include "stdio.h"

int main(void){
  int N,K;
  scanf("%d",&N);
  
  char S[N];

  scanf("%s",S);
  
  scanf("%d",&K);

  K-=1;

  S[K]= S[K]+0x20;
  
  printf("%s", S);
}