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 <bits/stdc++.h>
using namespace std;
#define REP(i,n) for(int i=0; i<(int)(n); i++)
#define RNG(i,from,to) for(int i=(from); i<(int)(to); i++)
#define gcd(i,j) __gcd((i), (j))
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<ll> vecll;
template<typename S, typename T> string to_string(pair<S, T> p) { return "("+to_string(p.first)+","+to_string(p.second)+")"; }
template<typename T> string to_string(T p[2]) { return "["+to_string(p[0])+","+to_string(p[1])+"]"; }
template<typename T> void println(T e){ cout << to_string(e) << endl; }
template<typename T> void println(const vector<T>& v){ cout << "[";for(const auto& e : v){ cout << to_string(e) << ","; }cout << "]";cout << endl; }
template<typename T> void println(const vector<vector<T>>& vv){ for(const auto& v : vv){ println(v); } }
template<typename Iter> void println(Iter first, Iter last){ for(auto it=first; it != last; it++){ cout << *it << " "; }; cout << endl; }
template<typename T> T mod_pow(T x, T n, const T &p) { T ret = 1; while(n > 0) { if(n & 1) (ret *= x) %= p; (x *= x) %= p; n >>= 1; } return ret; }
template<typename T> T mod_inv(T x, const T &p) { return mod_pow(x, p-2, p); }
const ll DVSR = 1e9+7;


int main(int argc, char const *argv[])
{
  string a,b,c; cin >> a >> b >> c;
  cout << a[0] << b[1] << c[2] << endl;
  return 0;
}