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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;

int main() 
{
  int n, k;
  string s;
  cin >> n >> k >> s;
  if (s.at(k - 1) == 'A') s.at(k - 1) = 'a';
  if (s.at(k - 1) == 'B') s.at(k - 1) = 'b';
  if (s.at(k - 1) == 'C') s.at(k - 1) = 'c';
  cout << s << endl;
}