T,A,B=map(int, input().split())
a,b=T//A,T//B
if T%A!=0:
  a+=1
if T%B!=0:
  b+=1
import math
C=(A*B)//math.gcd(A,B)
c=T//C
if T%C!=0:
  c+=1
print(a+b-c)