def Gcd(n, m):
    if m > 0:
        return Gcd(m, n % m)
    else:
        return n
def Lcm(n, m):
    return n / Gcd(n, m) * m
    
t, a, b = map(int, input().split())
A = (t - 1) // a
B = (t - 1) // b
C = (t - 1) // Lcm(a, b)
print(int(A + B - C + 1))