#yuki894

def gcd(x,y):
 while y:
  x,y=y,x%y
 return x

def lcm(x,y):
 return x*y//gcd(x,y)

t,a,b=map(int,raw_input().split())
if t%lcm(a,b):
 print t/a+t/b+1-t/lcm(a,b)
else:
 print t/a+t/b-t/lcm(a,b)