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: Wrong Answer)

package main

import (
	"fmt"
	"strings"
)

var N, K int
var S string

func main() {
	fmt.Scan(&N, &K, &S)
	if N >= K {
		a := strings.Split(S, "")
		var b string

		for i := 0; i < N; i++ {
			if i == K-1 {
				b += strings.ToLower(a[K-1])
			} else {
				b += a[i]
			}
		}
		fmt.Printf("%v %v\n%s\n", N, K, b)
	} else {
		panic("a")
	}
}