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<vector>
#include<map>
#include<algorithm>
#include<cmath>
#include<string>
#include<cstdlib>

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)   FOR(i,0,n)
#define MOD 1000000007

using namespace std;

typedef long long int ll;

const ll INF=(ll)1e18;

int main(){
  int N,K;
  cin >> N >> K;

  string S;
  cin >> S;
  transform(S.begin()+K-1, S.begin()+K, S.begin()+K-1, ::tolower);
  cout << S << endl;
}