Attempt

Please login to see your submissions result.

Problem

Given four integers ~A, B, C, D~. How many numbers ~X~ that ~X~ satisfied with condition:

• ~A \leq X \leq B~.
• ~X~ not divisible by ~C~ or not divisible.

Input

Single line contains four integers ~A, B, C, D~ seperated by spaces.

Output

The number of ~X~ that satisfied with condition.

Constraints

~1 \leq A \leq B \leq 10^{18}~.
~1 \leq C, D \leq 10^9~.

Sample

Explanation

In the Sample test #1, we have ~2~ number satisfied with condition is ~5, 7~.

In the Sample test #2, we have ~4~ number satisfied with condition is ~3, 6, 7, 9~.