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 C# (Mono 4.6.2.0) (judge verdict: Runtime Error)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace B___Palindromic_Numbers
{
    class Program
    {
        static void Main(string[] args)
        {
            int A = int.Parse(Console.ReadLine());
            int B = int.Parse(Console.ReadLine());
            int count = 0;

            for (int i = A; i <= B; ++i)
            {
                string s = i.ToString();

                System.Globalization.StringInfo si = new System.Globalization.StringInfo(s);

                string s1 = si.SubstringByTextElements(0, 1);

                string s2 = si.SubstringByTextElements(1, 1);

                string s4 = si.SubstringByTextElements(3, 1);

                string s5 = si.SubstringByTextElements(4, 1);

                if (s1 == s5 && s2 == s4)
                {
                    count += 1;
                }

                i = int.Parse(s);
            }

            Console.Write(count);
            Console.Read();
        }
    }
}