t,a,b=map(int,input().split())
ans=0

def gcd(a,b):
    if b==0:return a
    else :return gcd(b,a%b)
ans+=(t+a-1)//a+(t+b-1)//b
lcm=(a*b)//gcd(a,b)
ans-=(t+lcm-1)//lcm
print(ans)