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 int saishokobaisu(long int a, long int b) {
    long int r = a % b;
    long int x = a * b;
    while(r!=0){
      a = b;
      b = r;
      r = a % b;
    }

    return x/b;

}

int main(void){
    long int A,B,C,D;
    int count1=0, count2=0, count3=0, count4=0, count5=0, count6=0;
    int i=1, num=0;

    scanf("%lu %lu %lu %lu", &A, &B, &C, &D);

    while(1) {
        num = i*C;
        if(num > B) break;
        i++;
        count1++;
    }

    i = 1;
    num = 0;
    while(1) {
        num = i*D;
        if(num > B) break;
        i++;
        count2++;
    }

    i = 1;
    num = 0;
    while(1) {
        num = i*(saishokobaisu(C,D));
        if(num > B) break;
        i++;
        count3++;
    }

    i = 1;
    num = 0;
    while(1) {
        num = i*C;
        if(num > A) break;
        i++;
        count4++;
    }

    i = 1;
    num = 0;
    while(1) {
        num = i*D;
        if(num > A) break;
        i++;
        count5++;
    }

    i = 1;
    num = 0;
    while(1) {
        num = i*(saishokobaisu(C,D));
        if(num > A) break;
        i++;
        count6++;
    }

    printf("%lu\n", (B-(count1+count2-count3))-(A-(count4+count5-count6)));
    // printf("%d %d %d %d %d %d\n", count1, count2, count3, count4, count5, count6);

    return 0;
}