Problem:
Score : 100 points

Problem Statement

We have a 3×3 square grid, where each square contains a lowercase English letters.
The letter in the square at the i-th row from the top and j-th column from the left is c_{ij}.

Print the string of length 3 that can be obtained by concatenating the letters in the squares on the diagonal connecting the top-left and bottom-right corner of the grid, from the top-left to bottom-right.

Constraints

Input consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

c_{11}c_{12}c_{13}
c_{21}c_{22}c_{23}
c_{31}c_{32}c_{33}

Output

Print the string of length 3 that can be obtained by concatenating the letters on the diagonal connecting the top-left and bottom-right corner of the grid, from the top-left to bottom-right.

Sample Input 1

ant
obe
rec

Sample Output 1

abc

The letters in the squares on the diagonal connecting the top-left and bottom-right corner of the grid are a, b and c from top-right to bottom-left. Concatenate these letters and print abc.

Sample Input 2

edu
cat
ion

Sample Output 2

ean

Solution in Scala (2.11.7) (judge verdict: Runtime Error)

import scala.io.StdIn.{readLine}

object Main extends App {
  def isPalindromic(s: String): Boolean = {
    s(0) == s(4) && s(1) == s(3)
  }

  def nPalindromic(input: String): Int = {
    val ints = input.split(" ").map(_.toInt)
    nPalindromic(ints(0), ints(1))
  }

  def nPalindromic(start: Int, end: Int):Int = {
    (start to end).count(i => isPalindromic(i.toString))
  }

  println(nPalindromic(readLine()))
}