Problems
Interesting Product
Interesting Product
Find all possible values of product i \cdot j, if the integer values of variables i and j vary for i from a to b and j from c to d.
Input data
One line contains 4 numbers a, b, c and d (1 \le a, b, c, d \le 10, a can be greater than b, c can be greater than d).
Output data
Print the number of possible product values.
Examples
Input example #1
1 10 1 10
Output example #1
42