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: Wrong Answer)

#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <float.h>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <set>
#include <queue>
#include <limits>
#include <deque>
#include <locale>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <wchar.h>
#include <wctype.h>
#include <algorithm>
#include <bitset>
#include <map>
#include <iomanip>
#include <ios>
#include <iostream>
#include <vector>
#include <cwchar>
#include <cwctype>
#define mp make_pair
#define fs first
#define se second
#define memset(a,t) memset(a,t,sizeof(a))
#define all(v) v.begin(),v.end()
#define MN 0LL
#define Mx 200000005
#define Mn -Mx
#define MX 20000000000000005
using namespace std;
int readint(){
	char c;
	while(c=getchar(),(c<'0'||c>'9')&&c!='-');
	bool flag=(c=='-');
	if(flag)c=getchar();
	int x=0;
	while(c>='0'&&c<='9'){
		x=x*10+c-48;
		c=getchar();
	}
	return flag?-x:x;
}
inline string tos(int x){
	string s;
	while(x) s=(char)(x%10+'0')+s,x/=10;
	return s;
}
inline int toi(string s){
	int rt=0;
	for(int i=0;i<s.size();i++) rt=rt*10+(int)(s[i]-'0');
	return rt;
}
int main(){
	int i,j;
	long long n,m;
	cin>>n>>m;
	if(n>m) swap(n,m);
	if(n==1){
		if(m==1) cout<<1<<endl;
		else if(m==2) cout<<0<<endl;
		else{
			cout<<m-2<<endl;
		}
		return 0;
	}
	if(n==2){
		cout<<0<<endl;
		return 0;
	}
	cout<<(long long)((long long)(n-2)*(long long)(m-2))<<endl;
	return 0;
}