def Gcd(m,n) :
    while m % n != 0 :
        temp = n
        n = m % n
        m = temp
    return n

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

T -= 1

a = T // A
b = T // B
commonNum = A * B // Gcd(A,B)
aAndB = T // commonNum

print(a + b - aAndB + 1)