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

def gcd(x, y):
    while y:
        x, y = y, x % y
    return x

def lcm(x, y):
    return x // gcd(x, y) * y

C = lcm(A, B)

res = -(-T // A) - (-T // B) + (-T // C)

print(res)