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)

//Daniel Grzegorzewski
#include <bits/stdc++.h>
#pragma GCC optimize("O3")

#define MP make_pair
#define PB push_back
#define ST first
#define ND second

using namespace std;

typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef long long LL;

void init_ios() {
     ios_base::sync_with_stdio(0);
     cin.tie(0);
}

int n, k;
string s;

int main() {
  init_ios();
  cin >> n >> k >> s;
  --k;
  s[k] += 'a'-'A';
  cout<<s<<"\n";
}