Buggy python submission (verdict: Runtime Error):
import fractions
A,B,C,D=map(int,input().split())
L=C*D//fractions.gcd(C,D)

if A%C!=0 and A%D!=0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D+1)*D)//D+1-(((B-(A//L+1)*L)//L)+1)))
elif A%C==0 and A%D!=0:
    print((B-A+1)-(((B-(A//C)*C)//C+1)+((B-(A//D+1)*D)//D+1)-((B-(A//L+1)*L)//L+1)))
elif A%C!=0 and A%D==0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L+1)*L)//L-1))
elif A%C==0 and A%D==0 and A%L==0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D++1(B-(A//L)*L)//L-1))
elif A%C==0 and A%D==0 and A%L!=0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D+1+(B-(A//L+1)*L)//L-1))

Fixed submission:
import fractions
A,B,C,D=map(int,input().split())
L=C*D//fractions.gcd(C,D)

if A%C!=0 and A%D!=0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D+1)*D)//D+1-(((B-(A//L+1)*L)//L)+1)))
elif A%C==0 and A%D!=0:
    print((B-A+1)-(((B-(A//C)*C)//C+1)+((B-(A//D+1)*D)//D+1)-((B-(A//L+1)*L)//L+1)))
elif A%C!=0 and A%D==0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L+1)*L)//L-1))
elif A%C==0 and A%D==0 and A%L==0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L)*L)//L-1))
elif A%C==0 and A%D==0 and A%L!=0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L+1)*L)//L-1))

Buggy python submission (verdict: Runtime Error):
import math
A,B,C,D=map(int,input().split())
L=C*D//math.gcd(C,D)

if A%C!=0 and A%D!=0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D+1)*D)//D+1-(((B-(A//L+1)*L)//L)+1)))
elif A%C==0 and A%D!=0:
    print((B-A+1)-(((B-(A//C)*C)//C+1)+((B-(A//D+1)*D)//D+1)-((B-(A//L+1)*L)//L+1)))
elif A%C!=0 and A%D==0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L+1)*L)//L-1))
elif A%C==0 and A%D==0 and A%L==0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D++1(B-(A//L)*L)//L-1))
elif A%C==0 and A%D==0 and A%L!=0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D+1+(B-(A//L+1)*L)//L-1))



Fixed submission:
import fractions
A,B,C,D=map(int,input().split())
L=C*D//fractions.gcd(C,D)

if A%C!=0 and A%D!=0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D+1)*D)//D+1-(((B-(A//L+1)*L)//L)+1)))
elif A%C==0 and A%D!=0:
    print((B-A+1)-(((B-(A//C)*C)//C+1)+((B-(A//D+1)*D)//D+1)-((B-(A//L+1)*L)//L+1)))
elif A%C!=0 and A%D==0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L+1)*L)//L-1))
elif A%C==0 and A%D==0 and A%L==0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L)*L)//L-1))
elif A%C==0 and A%D==0 and A%L!=0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L+1)*L)//L-1))

Buggy python submission (verdict: Runtime Error):
import math
A,B,C,D=map(int,input().split())
L=C*D//math.gcd(C,D)

if A%C!=0 and A%D!=0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D+1)*D)//D+1-(((B-(A//L+1)*L)//L)+1)))
elif A%C==0 and A%D!=0:
    print((B-A+1)-(((B-(A//C)*C)//C+1)+((B-(A//D+1)*D)//D+1)-((B-(A//L+1)*L)//L+1)))
elif A%C!=0 and A%D==0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L+1)*L)//L-1))
elif A%C==0 and A%D==0 and A%L==0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D++1(B-(A//L)*L)//L-1))
elif A%C==0 and A%D==0 and A%L!=0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D+1+(B-(A//L+1)*L)//L-1))

Fixed submission:
import fractions
A,B,C,D=map(int,input().split())
L=C*D//fractions.gcd(C,D)

if A%C!=0 and A%D!=0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D+1)*D)//D+1-(((B-(A//L+1)*L)//L)+1)))
elif A%C==0 and A%D!=0:
    print((B-A+1)-(((B-(A//C)*C)//C+1)+((B-(A//D+1)*D)//D+1)-((B-(A//L+1)*L)//L+1)))
elif A%C!=0 and A%D==0:
    print((B-A+1)-((B-(A//C+1)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L+1)*L)//L-1))
elif A%C==0 and A%D==0 and A%L==0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L)*L)//L-1))
elif A%C==0 and A%D==0 and A%L!=0:
    print((B-A+1)-((B-(A//C)*C)//C+1+(B-(A//D)*D)//D+1-(B-(A//L+1)*L)//L-1))