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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <math.h>
#include <string>
#include <string.h>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <stdlib.h>
#include <deque>  
#include <iomanip>

using namespace std;

using ll = long long;
#define INF 1e9
#define MOD 1e9 + 7
#define rep(i, n) for(int i = 0; i < n; i++)
#define loop(i, a, n) for(int i = a; i < n; i++)
#define all(in) in.begin(), in.end()
int main(){
    char c[3][3];
    rep(i, 3)rep(k, 3) cin >> c[i][k];
    string ans = "";
    rep(i, 3)rep(k, 3){
        if(i == k) ans += c[i][k];
    }
    cout << ans << endl;
    return 0;
}