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 <stdio.h>
#include <assert.h>
#include <fstream>
#include <iostream>
#include <algorithm>
#include <array>
#include <vector>
#include <queue>
#include <set>
#include <cmath>
//#include <unordered_map>
//#include <unordered_set>
//#include <boost/container/static_vector.hpp>
//#include <boost/unordered_set.hpp>
//#include <boost/unordered_map.hpp>
//#include <unistd.h>

//#include <cv.h>
//#include <highgui.h>
#include <stdlib.h>
#include <string>

int N, K;
std::string S;

int main(int argc, char **argv) {
    std::cin >> N >> K;
    std::cin >> S;

    if (S[K-1] == 'A') {
        S[K-1] = 'a';
    } else if (S[K-1] == 'B') {
        S[K-1] = 'b';
    } else {
        S[K-1] = 'c';
    }
    
    std::cout << S << std::endl;

    return 0;
}