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: Runtime Error)

package main

import (
	"fmt"
	//"math"
)

func main() {
	var n,k int 
	var s string
	str := ""
	fmt.Scanf("%d %d", &n,&k)
	fmt.Scanf("%s", &s)
	for i := 0 ; i<k;i++{
		str += string(s[i])
	}
	str += string(byte(s[k]) + 32)
	for i := k+1 ; i<len(s);i++{
		str += string(s[i])
	}
	print(str)
}