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: Time Limit Exceeded)

#include <stdio.h>
typedef unsigned long long ULL;

ULL gcd(ULL a, ULL b);
ULL lcm(ULL a, ULL b);

int main(){
    ULL a, b, c, d, ans = 0;
    scanf("%llu %llu %llu %llu", &a, &b, &c, &d);

    for(ULL u = a; u <= b; u++){
        if(u % c != 0 && u % d != 0){
            ans++;
        }
    }
    printf("%llu\n", ans);
    return 0;
}