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"

func main() {
	var n, k int
	var s string
	fmt.Scan(&n, &k, &s)
	for i, c := range s {
		if i == k-1 {
			fmt.Printf("%c", c+0x20)
		} else {
			fmt.Printf("%c", c)
		}
	}
	fmt.Printf("\n")
}