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: Runtime Error)

#include<stdio.h>

int main(){
	char si[50];
	int n,k;
	char s;
	int x;
	
	scanf("%d" "%d",&n,&k);	
	scanf("%s",&s);
	if(si[k]=='A'){
	si[k]='a';
 	 }else if(si[k]=='B'){
	si[k]='b';
 	 }else if(si[k]=='C'){
	si[k]='c';
 	 }
	for(x=0;x<n;x++)
	printf("%c",si[x]);
return 0;
}