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 e,d;
    char f[e];

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

    if(f[d-1]=='A'){
        f[d-1]='a';
        printf("%s",f);
    }else if(f[d-1]=='B'){
        f[d-1]='b';
        printf("%s",f);
    }else{
        f[d-1]='c';
        printf("%s",f);
    }
    return 0;
}