HackerEarth The Prime Cells problem solution

In this HackerEarth The Prime Cells problem solution You are given a grid of size n x n filled with numbers in each of its cells. Now you need to count total cells in the grid such that the sum of the numbers on its top, left, right and bottom cells is a prime number. In case there is no cell in a particular direction assume the number to be 0.

HackerEarth The Prime Cells problem solution.

#include <bits/stdc++.h>
#define ll long long
#define endl '\n'
const int mod = 1e9 + 7;
using namespace std;

int main() {

int prime[401];

for(int i=0;i<=401;i++)

       prime[i]=1;
   prime[0]=0;
   prime[1]=0;
   for(int i=2;i<=401;i++){
       if(prime[i]==1){
           for(int j=2*i;j<=401;j=j+i)
               prime[j]=0;

       }

   }
   int n;

   cin>>n;

   int a[n+2][n+2];

   for(int i=0;i<n+2;i++){

       for(int j=0;j<n+2;j++)

           a[i][j]=0;

   }

   for(int i=1;i<=n;i++){

       for(int j=1;j<=n;j++)

           cin>>a[i][j];

   }
   int sum=0;
   int count=0;
   for(int i=1;i<=n;i++){

       for(int j=1;j<=n;j++){
           int k=a[i][j-1];
           int d=a[i][j+1];
           int e=a[i-1][j];
           int f=a[i+1][j];
           sum=k+d+e+f;
           if(prime[sum]==1)
              count++;

       }

   }

   cout<<count<<endl;

}