def gcd(x, y):
    if y == 0:
        return x
    return gcd(y, x % y)

T, A, B = map(int, input().split())
g = gcd(A, B)
l = A * B / g
print(int((T + A - 2) // A + (T + B - 2) // B - (T + l - 2) // l))