C++ Program:

Example:

#include <iostream>
using namespace std;

int main() {
  int n;
  cout<<"Enter N of N X N magic matrix(must be odd number) :";
  cin>>n;
  if(n%2!=0) {
    cout<<"Sum of rows|columns|diagonals of "<<n<<"x"<<n<<" magic matrix : ";
    cout<<(n*(n*n+1))/2;
  }
  else{
    cout<<"N must be an odd number";
  }
  return 0;
}

Output:

  Enter N of N X N magic matrix(must be odd number) : 5
  Sum of rows|columns|diagonals of 5 x 5 magic matrix : 65

Remember : Magic matrix are always odd value matrix

like : 3x3,5x5,7x7,.....

So, you must first check it for an Odd value

(n*(n*n+1))/2 //Formula to calculate the sum

To check for odd value

n%2!=0