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 PyPy3 (2.4.0) (judge verdict: Runtime Error)

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

long long N, K;
string S;

int main(){
	cin >> N >> K;
	cin >> S;
	S[K-1] = S[K-1] - ('A' - 'a');
	cout << S << endl;
}