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: Wrong Answer)

#include<iostream>
using namespace std;
int main(){
  int n,k,i=1,m=1;
  double ans=0,P=1;
  cin >> n >> k;
  for(i=1;i<=n;i++){
    P=(double)1/n;
    for(m=i;m<k;){
      P=P/2;
      m=m*2;
    }
    ans=ans+P;
  }
  printf("%.10lf",ans);
  return 0;
}