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 Kotlin (1.0.0) (judge verdict: Runtime Error)

fun main(args: Array<String>){
    for (i in 0..2) {
        val line: String = readLine() as String
        val a =Array(5, {i -> line[i]-'0'})
        val b =Array(5, {i -> line[i+6]-'0'})
        var min=a[0]*100+a[1]*10+a[2]
        var max=b[0]*100+b[1]*10+b[2]

        if(b[1]>b[3]||(b[1]==b[3]&&b[0]>b[4])){//単に反転したやつがもとのを超える
            max-=1
        }
        if(a[1]<a[3]||(a[1]==a[3]&&a[0]<a[4])){//単に反転したやつがもとのより小さい
            min+=1
        }
        if(max>=min)print(max-min+1)
        else print(0)

    }
}