def gcd(x,y):
    if y <= 0:
        return x
    return gcd(y, x%y)
def lcm(x,y):
    return x*y//gcd(x,y)
T,A,B = map(int,input().split())
if T%lcm(A,B) == 0:
    s = T//lcm(A,B) - 1
else:
    s = T//lcm(A,B)
if T%A == 0:
    t = T//A - 1
else:
    t = T//A
if T%B == 0:
    u = T//B - 1
else:
    u = T//B
print(1-s+t+u)