import java.util.*;

public class Main {


    public static long lcm(long m, long n){
        return m*n/gcd(m,n);
    }

    public static long gcd(long c, long d){
        if (c<d){return gcd(d,c);}
        if(d==0){return c;}
        return gcd(d, c%d);
    }


    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        long a = sc.nextLong();
        long b = sc.nextLong();
        long c = sc.nextLong();
        long d = sc.nextLong();

//        long num[] = new long[b-a+1];
//        for (long i=0; i<b-a+1; i++){
//            num[i] = a+i;
//        }

        long count=0;

//        long total = b-a+1;


//        b = b-(b/c)-(b/d)+b/lcm(c,d);
//        a = a-1-((a-1)/c)-((a-1)/d)+(a-1)/lcm(c,d);

//        count = b-a;

        long c_count=0;
        long d_count=0;
        long cd_count=0;

        c_count = b/c-(a-1)/c;
        d_count = b/d-(a-1)/d;
        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//
//        c_count = b/c - (a-1)/c;
//        d_count = b/d - (a-1)/d;
//        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//        if (((c-(a%c))+b%c)>c){
//            c_count += (b-a+1)/c-1;
//        }else{
//            c_count += (b-a+1)/c;
//        }
//
//
//        if (((d-(a%d))+b%d)>d){
//            d_count += (b-a+1)/d-1;
//        }else{
//            d_count += (b-a+1)/d;
//        }
//
//
//
//
//        if (((lcm(c,d)-(a%lcm(c,d))+b%lcm(c,d))>lcm(c,d))){
//            cd_count += (b-a+1)/lcm(c,d)-1;
//        }else{
//            cd_count += (b-a+1)/lcm(c,d);
//        }

        count = (b-a+1)-c_count-d_count+cd_count;

        System.out.println(count);

    }
}
 import java.util.*; util.* java public class Main {


    public static long lcm(long m, long n){
        return m*n/gcd(m,n);
    }

    public static long gcd(long c, long d){
        if (c<d){return gcd(d,c);}
        if(d==0){return c;}
        return gcd(d, c%d);
    }


    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        long a = sc.nextLong();
        long b = sc.nextLong();
        long c = sc.nextLong();
        long d = sc.nextLong();

//        long num[] = new long[b-a+1];
//        for (long i=0; i<b-a+1; i++){
//            num[i] = a+i;
//        }

        long count=0;

//        long total = b-a+1;


//        b = b-(b/c)-(b/d)+b/lcm(c,d);
//        a = a-1-((a-1)/c)-((a-1)/d)+(a-1)/lcm(c,d);

//        count = b-a;

        long c_count=0;
        long d_count=0;
        long cd_count=0;

        c_count = b/c-(a-1)/c;
        d_count = b/d-(a-1)/d;
        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//
//        c_count = b/c - (a-1)/c;
//        d_count = b/d - (a-1)/d;
//        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//        if (((c-(a%c))+b%c)>c){
//            c_count += (b-a+1)/c-1;
//        }else{
//            c_count += (b-a+1)/c;
//        }
//
//
//        if (((d-(a%d))+b%d)>d){
//            d_count += (b-a+1)/d-1;
//        }else{
//            d_count += (b-a+1)/d;
//        }
//
//
//
//
//        if (((lcm(c,d)-(a%lcm(c,d))+b%lcm(c,d))>lcm(c,d))){
//            cd_count += (b-a+1)/lcm(c,d)-1;
//        }else{
//            cd_count += (b-a+1)/lcm(c,d);
//        }

        count = (b-a+1)-c_count-d_count+cd_count;

        System.out.println(count);

    }
} Main public static long lcm(long m, long n){
        return m*n/gcd(m,n);
    } lcm {
        return m*n/gcd(m,n);
    } return m*n/gcd(m,n); m*n/gcd(m,n) m*n m n gcd(m,n) gcd m n long m m long n n public static long gcd(long c, long d){
        if (c<d){return gcd(d,c);}
        if(d==0){return c;}
        return gcd(d, c%d);
    } gcd {
        if (c<d){return gcd(d,c);}
        if(d==0){return c;}
        return gcd(d, c%d);
    } if (c<d){return gcd(d,c);} c<d c d {return gcd(d,c);} return gcd(d,c); gcd(d,c) gcd d c if(d==0){return c;} d==0 d 0 {return c;} return c; c return gcd(d, c%d); gcd(d, c%d) gcd d c%d c d long c c long d d public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        long a = sc.nextLong();
        long b = sc.nextLong();
        long c = sc.nextLong();
        long d = sc.nextLong();

//        long num[] = new long[b-a+1];
//        for (long i=0; i<b-a+1; i++){
//            num[i] = a+i;
//        }

        long count=0;

//        long total = b-a+1;


//        b = b-(b/c)-(b/d)+b/lcm(c,d);
//        a = a-1-((a-1)/c)-((a-1)/d)+(a-1)/lcm(c,d);

//        count = b-a;

        long c_count=0;
        long d_count=0;
        long cd_count=0;

        c_count = b/c-(a-1)/c;
        d_count = b/d-(a-1)/d;
        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//
//        c_count = b/c - (a-1)/c;
//        d_count = b/d - (a-1)/d;
//        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//        if (((c-(a%c))+b%c)>c){
//            c_count += (b-a+1)/c-1;
//        }else{
//            c_count += (b-a+1)/c;
//        }
//
//
//        if (((d-(a%d))+b%d)>d){
//            d_count += (b-a+1)/d-1;
//        }else{
//            d_count += (b-a+1)/d;
//        }
//
//
//
//
//        if (((lcm(c,d)-(a%lcm(c,d))+b%lcm(c,d))>lcm(c,d))){
//            cd_count += (b-a+1)/lcm(c,d)-1;
//        }else{
//            cd_count += (b-a+1)/lcm(c,d);
//        }

        count = (b-a+1)-c_count-d_count+cd_count;

        System.out.println(count);

    } main {

        Scanner sc = new Scanner(System.in);

        long a = sc.nextLong();
        long b = sc.nextLong();
        long c = sc.nextLong();
        long d = sc.nextLong();

//        long num[] = new long[b-a+1];
//        for (long i=0; i<b-a+1; i++){
//            num[i] = a+i;
//        }

        long count=0;

//        long total = b-a+1;


//        b = b-(b/c)-(b/d)+b/lcm(c,d);
//        a = a-1-((a-1)/c)-((a-1)/d)+(a-1)/lcm(c,d);

//        count = b-a;

        long c_count=0;
        long d_count=0;
        long cd_count=0;

        c_count = b/c-(a-1)/c;
        d_count = b/d-(a-1)/d;
        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//
//        c_count = b/c - (a-1)/c;
//        d_count = b/d - (a-1)/d;
//        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//        if (((c-(a%c))+b%c)>c){
//            c_count += (b-a+1)/c-1;
//        }else{
//            c_count += (b-a+1)/c;
//        }
//
//
//        if (((d-(a%d))+b%d)>d){
//            d_count += (b-a+1)/d-1;
//        }else{
//            d_count += (b-a+1)/d;
//        }
//
//
//
//
//        if (((lcm(c,d)-(a%lcm(c,d))+b%lcm(c,d))>lcm(c,d))){
//            cd_count += (b-a+1)/lcm(c,d)-1;
//        }else{
//            cd_count += (b-a+1)/lcm(c,d);
//        }

        count = (b-a+1)-c_count-d_count+cd_count;

        System.out.println(count);

    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc long b = sc.nextLong(); b sc.nextLong() sc.nextLong sc long c = sc.nextLong(); c sc.nextLong() sc.nextLong sc long d = sc.nextLong(); d sc.nextLong() sc.nextLong sc long count=0; count 0 long c_count=0; c_count 0 long d_count=0; d_count 0 long cd_count=0; cd_count 0 c_count = b/c-(a-1)/c c_count b/c-(a-1)/c b/c b c (a-1)/c (a-1) a 1 c d_count = b/d-(a-1)/d d_count b/d-(a-1)/d b/d b d (a-1)/d (a-1) a 1 d cd_count = b/lcm(c,d)-(a-1)/lcm(c,d) cd_count b/lcm(c,d)-(a-1)/lcm(c,d) b/lcm(c,d) b lcm(c,d) lcm c d (a-1)/lcm(c,d) (a-1) a 1 lcm(c,d) lcm c d count = (b-a+1)-c_count-d_count+cd_count count (b-a+1)-c_count-d_count+cd_count (b-a+1)-c_count-d_count (b-a+1)-c_count-d_count (b-a+1) b-a b a 1 c_count d_count cd_count System.out.println(count) System.out.println System.out System System.out count String[] args args public class Main {


    public static long lcm(long m, long n){
        return m*n/gcd(m,n);
    }

    public static long gcd(long c, long d){
        if (c<d){return gcd(d,c);}
        if(d==0){return c;}
        return gcd(d, c%d);
    }


    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        long a = sc.nextLong();
        long b = sc.nextLong();
        long c = sc.nextLong();
        long d = sc.nextLong();

//        long num[] = new long[b-a+1];
//        for (long i=0; i<b-a+1; i++){
//            num[i] = a+i;
//        }

        long count=0;

//        long total = b-a+1;


//        b = b-(b/c)-(b/d)+b/lcm(c,d);
//        a = a-1-((a-1)/c)-((a-1)/d)+(a-1)/lcm(c,d);

//        count = b-a;

        long c_count=0;
        long d_count=0;
        long cd_count=0;

        c_count = b/c-(a-1)/c;
        d_count = b/d-(a-1)/d;
        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//
//        c_count = b/c - (a-1)/c;
//        d_count = b/d - (a-1)/d;
//        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//        if (((c-(a%c))+b%c)>c){
//            c_count += (b-a+1)/c-1;
//        }else{
//            c_count += (b-a+1)/c;
//        }
//
//
//        if (((d-(a%d))+b%d)>d){
//            d_count += (b-a+1)/d-1;
//        }else{
//            d_count += (b-a+1)/d;
//        }
//
//
//
//
//        if (((lcm(c,d)-(a%lcm(c,d))+b%lcm(c,d))>lcm(c,d))){
//            cd_count += (b-a+1)/lcm(c,d)-1;
//        }else{
//            cd_count += (b-a+1)/lcm(c,d);
//        }

        count = (b-a+1)-c_count-d_count+cd_count;

        System.out.println(count);

    }
} public class Main {


    public static long lcm(long m, long n){
        return m*n/gcd(m,n);
    }

    public static long gcd(long c, long d){
        if (c<d){return gcd(d,c);}
        if(d==0){return c;}
        return gcd(d, c%d);
    }


    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        long a = sc.nextLong();
        long b = sc.nextLong();
        long c = sc.nextLong();
        long d = sc.nextLong();

//        long num[] = new long[b-a+1];
//        for (long i=0; i<b-a+1; i++){
//            num[i] = a+i;
//        }

        long count=0;

//        long total = b-a+1;


//        b = b-(b/c)-(b/d)+b/lcm(c,d);
//        a = a-1-((a-1)/c)-((a-1)/d)+(a-1)/lcm(c,d);

//        count = b-a;

        long c_count=0;
        long d_count=0;
        long cd_count=0;

        c_count = b/c-(a-1)/c;
        d_count = b/d-(a-1)/d;
        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//
//        c_count = b/c - (a-1)/c;
//        d_count = b/d - (a-1)/d;
//        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//        if (((c-(a%c))+b%c)>c){
//            c_count += (b-a+1)/c-1;
//        }else{
//            c_count += (b-a+1)/c;
//        }
//
//
//        if (((d-(a%d))+b%d)>d){
//            d_count += (b-a+1)/d-1;
//        }else{
//            d_count += (b-a+1)/d;
//        }
//
//
//
//
//        if (((lcm(c,d)-(a%lcm(c,d))+b%lcm(c,d))>lcm(c,d))){
//            cd_count += (b-a+1)/lcm(c,d)-1;
//        }else{
//            cd_count += (b-a+1)/lcm(c,d);
//        }

        count = (b-a+1)-c_count-d_count+cd_count;

        System.out.println(count);

    }
} Main
import java.util.*;

public class Main {


    public static long lcm(long m, long n){
        return m*n/gcd(m,n);
    }

    public static long gcd(long c, long d){
        if (c<d){return gcd(d,c);}
        if(d==0){return c;}
        return gcd(d, c%d);
    }


    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        long a = sc.nextLong();
        long b = sc.nextLong();
        long c = sc.nextLong();
        long d = sc.nextLong();

//        long num[] = new long[b-a+1];
//        for (long i=0; i<b-a+1; i++){
//            num[i] = a+i;
//        }

        long count=0;

//        long total = b-a+1;


//        b = b-(b/c)-(b/d)+b/lcm(c,d);
//        a = a-1-((a-1)/c)-((a-1)/d)+(a-1)/lcm(c,d);

//        count = b-a;

        long c_count=0;
        long d_count=0;
        long cd_count=0;

        c_count = b/c-(a-1)/c;
        d_count = b/d-(a-1)/d;
        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//
//        c_count = b/c - (a-1)/c;
//        d_count = b/d - (a-1)/d;
//        cd_count = b/lcm(c,d)-(a-1)/lcm(c,d);
//
//        if (((c-(a%c))+b%c)>c){
//            c_count += (b-a+1)/c-1;
//        }else{
//            c_count += (b-a+1)/c;
//        }
//
//
//        if (((d-(a%d))+b%d)>d){
//            d_count += (b-a+1)/d-1;
//        }else{
//            d_count += (b-a+1)/d;
//        }
//
//
//
//
//        if (((lcm(c,d)-(a%lcm(c,d))+b%lcm(c,d))>lcm(c,d))){
//            cd_count += (b-a+1)/lcm(c,d)-1;
//        }else{
//            cd_count += (b-a+1)/lcm(c,d);
//        }

        count = (b-a+1)-c_count-d_count+cd_count;

        System.out.println(count);

    }
}

