Square Matrix-Corner Elements Sum

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#include<stdio.h>
int main()
{
    int sum=0,a[10][10],i,j,n;
    printf("Enter the order N of matrix : ");
    scanf("%d",&n); //n*n matrix
    printf("Enter the matrix elements : ");
    for(i=0;i<n;i++)
    {
        for(j=0;j<n;j++)
        {
            scanf("%d",&a[i][j]);
        }
    }
    for(i=0;i<n;i++)
    {
        if((i==0)||(i==n-1)) //select only first and last row
        {
            for(j=0;j<n;j++)
            {
                if((j==0)||(j==n-1)) //select only first and last column 
                {
                    sum=sum+a[i][j];
                }
            }
        }
    }
    printf("%d",sum);
    return 0;
    
}