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 Scala (2.11.7) (judge verdict: Accepted)

object Main {
    def main(args: Array[String]): Unit = {
      val lines = io.Source.stdin.getLines().toSeq
      println(solve(lines))
    }

    def solve(lines: Seq[String]): String = {
      val Array(n, k) = lines.head.split(" ").map(_.toInt)
      val s = lines.tail.head.split("").filter(_.length > 0).take(n)
      debug(n, k, s)

      val str = s.map(v => v).toArray
      str(k - 1) = str(k - 1).toLowerCase()
      str.mkString("")
    }

    private def debug(x: Any): Unit = {
      if (System.getenv("LOCAL_DEBUG") != null) println(x)
    }
  }