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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"fmt"
	"strings"
)

func main() {
	var n, k int
	var s string
	fmt.Scan(&n, &k, &s)

	var result string
	for i := 1; i <= n; i++ {
		if i == k {
			str := s[i-1:i]
			result += strings.ToLower(str)
		} else {
			result += s[i-1:i]
		}
	}

	fmt.Println(result)
}