def gcd(m, n):
    while n:
        m, n = n, m % n
    return m
def lcm(m, n):
    return m//gcd(m, n)*n
T, A, B = map(int, input().split())
print((T-1)//A + (T-1)//B - (T-1)//lcm(A, B) + 1)