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 9.2.1) (judge verdict: Accepted)

#include <iostream>
using namespace std;
int main(){
  int a,b;
  string s;
  cin >> a >> b;
  cin >> s;
  if (islower(s[b-1])){
    s[b-1]=toupper(s[b-1]);
    cout << s << endl;
  }
  else {
    s[b-1]=tolower(s[b-1]);
    cout << s << endl;
  }
}