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

def gcd(a, b):
    if a < b:
        a,b = b,a
    if a % b == 0:
        return b
    return gcd(b, a%b)

lcm = A*B//gcd(A, B)
ans = (T-1)//A + (T-1)//B - (T-1)//lcm + 1
print(ans)