Problem:
Score : 300 points

Problem Statement

You are given four integers A, B, C, and D. Find the number of integers between A and B (inclusive) that can be evenly divided by neither C nor D.

Constraints

1\leq A\leq B\leq 10^{18}

1\leq C,D\leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

A B C D

Output

Print the number of integers between A and B (inclusive) that can be evenly divided by neither C nor D.

Sample Input 1

4 9 2 3

Sample Output 1

2

5 and 7 satisfy the condition.

Sample Input 2

10 40 6 8

Sample Output 2

23

Sample Input 3

314159265358979323 846264338327950288 419716939 937510582

Sample Output 3

532105071133627368

Solution in Pascal (FPC 2.6.2) (judge verdict: Runtime Error)

Uses math;
var A,B,C,D,pCD,i,nCD,nC,nD:int64;
begin
 read(A,B,C,D);pCD:=1;
for i := 2 to max(C,D) do if (C mod i = 0) or (D mod i = 0) then pCD:=pCD*i;
 nCD:=(B-A) div pCD;
 nC:=(B-A) div C;
 nD:=(B-A) div D;
 write(B-A-nC-nD+nCD);
end.