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 <cstdlib>
#include <string>
#include <vector>
#include <stack>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <math.h>
#include <stdio.h>
#include <ctype.h>
#include <ios> 
#include <iomanip>
using namespace std;

#define N_MAX   (100000)
#define LL_MAX_NUM (1LL<<60)
#define INF 1e7

typedef long long ll;
typedef long long int lli;

int main() {
	int n, k; string s; cin >> n >> k >> s;
    transform (s.begin()+(k-1), s.begin()+k, s.begin()+(k-1), ::tolower);
	cout << s << endl;
	return 0;
}