C-Program to find the diagonal Sum of a Matrix

#include<stdio.h>
main()
{
int a[50][50],m,n;
  int i,j,d1=0,d2=0;
  printf("Enter no. of rows and columns(order)\t");
  scanf("%d%d",&m,&n);
  printf("Enter the elements of matrix:\n");
  if(m==n)
  {
    for(i=0; i<m; i++)
    for(j=0; j<n; j++)
          scanf("%d",&a[i][j]);
  printf("matrix representation of above elemnts is\n");
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
printf("%d\t",a[i][j]);
printf("\n");
}
for(i=0,j=n-1;i<m||j>=0;i++,j--)
    {
        d1=d1+a[i][i];
        d2=d2+a[i][j];
    }
    printf("\nFirst diagonal's SUM\t%d",d1);
    printf("\nSecond diagonal's SUM\t %d",d2);
  }
  else
  printf("This program is only applicable to square matrices!!!");
 
}

output