check the maximum product in diagonal going through up - right
if ( ( i - 3 ) >= 0 && ( j - 1 ) <= 0 ) { result = arr [ i , j ] * arr [ i - 1 , j + 1 ] * arr [ i - 2 , j + 2 ] * arr [ i - 3 , j + 3 ] ; if ( max < result ) max = result ; } } } return max ; }