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 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <math.h>

int main(void){
	
	int n=0,k=0;
	int p=0;
	int i=0;
	double sum=0;
	
	scanf("%d %d",&n,&k);
	
	for(i=1;i<=n;i++){
		p=0;
		while(i*pow(2.0,(double)p)<=(double)k){
			p++;
		}
	
		sum+=1.0/(double)n/pow(2.0,(double)p);
	}
	
	printf("%.12f\n",sum);
	
	return 0;
}