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 C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>

long long gcd(long long x,long long y){
    long long r;
    while((r = x%y) != 0){/*ユークリッドの互除法*/
    x=y;
    y=r;
    }
    return y;
}

long long LCM(long long x, long long y){
return ((x)/gcd(x,y))*(y/gcd(x,y));
}
int main(){
  long long A,B,C,D,i,j,k,ans=0;
  
  scanf("%lld %lld %lld %lld",&A,&B,&C,&D);
  A--;
  ans = (B-B/C - B/D + B/LCM(C,D)) - (A-A/C - A/D + A/LCM(C,D));
  printf("%lld\n",ans);
  return 0;
}