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 FOR(i,n) for(int i=0;i<n;i++)
#define why(n,x) int n;while(cin >>n,n!=x)
#define iFOR(i,x,n)for(int i=x;i<n;i++)
#define unless(flg) if ( !(flg) )
#define read cin<<
#define echo cout<<
#define fin <<'\n'
#define __ <<" "<<
#define ___ <<" "
#define bash push_back
#define ALL(x) x.begin(),x.end()
#define SWAP(a,b) ((a != b) && (a += b,b = a - b,a -= b))
#define cinf(n,x) for(int UNCH=0;UNCH<(n);UNCH++) cin >> x[UNCH];
#define fcin(n,x) for(int UNCH=1;UNCH<=(n);UNCH++) cin>> x[UNCH];
#define memmin(x) memset((x),-1,sizeof((x)))
#define memzer(x) memset((x), 0,sizeof((x)))
#define meminf(x) memset((x),0x3f,sizeof((x)))
#define int long long
typedef long long ll;
typedef pair < int , int >  pii;
typedef vector < int > vit;
typedef map < string , int > mstit;
typedef vector < pii > vpi ;
typedef greater < pii > gpi;
typedef priority_queue < pii , vpi , gpi > dijk ;
static const signed int INF = 0x3f3f3f3f;
static const signed long long LINF = 0x3f3f3f3f3f3f3f3fLL;
static const signed int SMOD = 1000000007;
static const signed int NMOD = 1000000009;
static const signed int dx[]={1,0,-1,0,1,1,-1,-1};
static const signed int dy[]={0,-1,0,1,-1,1,-1,1};

bool inside(int x,int y,int w,int h){return (x>=0 && y>=0 && x<w && y<h);}
template<class T>T abs(T &x){return x<0 ? -x : x;}
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
int qp(int a,ll b,int mo){int ans=1;do{if(b&1)ans=1ll*ans*a%mo;a=1ll*a*a%mo;}while(b>>=1);return ans;}
int gcd(int a,int b){return b?gcd(b,a%b):a;}



signed main(){
    string str[3];
    FOR(i,3)
        cin >> str[i];
    cout << str[0][0] << str[1][1] << str[2][2] fin;
  
  return 0;
}



struct xyz{ xyz(){ cin.tie(0), ios::sync_with_stdio(false); cout <<fixed<<setprecision(12);};}xyzzy;