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 <iostream>
#include <vector>

using namespace std;

int main() {
  size_t N, K;
  cin >> N >> K;
  string S;
  cin >> S;
  const char* s = S.c_str();
  auto l = locale::classic();
  for (size_t i = 0; i < N; i++) {
    if (i + 1 == K) {
      cout << tolower(s[i], l);
    } else {
      cout << s[i];
    }
  }
  cout << endl;
  return 0;
}