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 <bits/stdc++.h>

using namespace std;

#define mp make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) ((int)(x).size())
#define whole(x) (x).begin(), (x).end()

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair < int, int > pii;
typedef pair < ll, ll > pll;

const int N = int(2000) + 2;
const int LG = 20;
const ll mod = 998244353;
const int INF = 2147483647;
const ll linf = 1e18;
const ld pi = acos(-1);
const ld EPS = 1e-10;

int n, k;
string s;
int main (){
    cin >> n >> k >> s;
    s[k - 1] = tolower(s[k - 1]);
    cout << s << "\n";
}