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>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <queue>
#include <cstring>
#include <climits>
using namespace std;
#define ll long long
#define FOR(i,n) for(int i=0;i<n;i++)
#define sz(x) (int)(x.size())
#define all(x) (x).begin(),(x).end()
template<typename tp> void read(tp &x) {cin >> x;}
template<typename tp, typename... Args> void read(tp& x, Args&... args) {read(x);read(args...);}
const int mxN = (int)1e5,INF = (int)1e9,MOD = (int)1e9+7;

void solve()
{
	int n,k;
	string s;
	read(n,k,s);
	s[k-1] = tolower(s[k-1]);
	cout << s;
}

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int test = 1;
	//read(test);
	while(test--)
		solve();
	return 0;
}