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>
#include <stdlib.h>
#include <string.h>
#include <math.h>
int compare_int(const void *a, const void *b)
{
//    return *(int*)a - *(int*)b;
    return *(long long*)a - *(long long*)b;
}
//  qsort(A, b, sizeof(int), compare_int);

int main()
{
  int a ,b, c, d, e, X, Y;
//  long long  b, c, d, e, X, Y;
  //  double  c;
  long long  A[100003]={};
  int  B[100003]={};
  int  C[100003]={};

  int  flag[103]={};

//  long long  a, b, c, d, X, Y;
  char s[101]={};
//  int N, M;
//  int A[1000000001]={};
//  long long  C[101]={};
  int i,j,k;
//  int flag=0;
  int tmp=0;
//  int min=1000000;
  long long min=100000001;
  int len=0;
  int cnt=0;
  int num=0;
  double ans=1000;
  int max=0;
//  char alp[26]={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};

  //  a=0;
//  scanf("%lld %lld", &a, &b);
  scanf("%d%d", &a,&c);
//  cnt = strlen(t);
// printf("%d\n",a);
    scanf("%s", &s);
/*  
  for(i=0;i<a;i++){
//    printf("%lld ",A[i]);
    if(A[i]==1) {
      printf("1\n");
      return 0;
    }
  }    
*/
  s[c-1]=s[c-1]+32;
  printf("%s\n",s);

  //  //  if(flag==0)   printf("TLE\n");
//    if(max < cnt - max)  printf("Yes\n");
//    else  printf("No\n");
  
return 0;
}