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

def gcd(x, y):
    if x < y:
        x, y = y, x
    if x % y == 0:
        return y
    return gcd(y, x % y)
T -= 1

count = 1
count += T // A
count += T // B

lcm = (A * B) // gcd(A, B)
count -= T // lcm

print (count)