def gcd(a, b):
    while b:
        a, b = b, a%b
    return a

def lcm(a, b):
    return a*b // gcd(a, b)

T, A, B = map(int, input().split())

print((T-1)//A + (T-1)//B - (T-1)//lcm(A, B) + 1)