from fractions import gcd

def lcm(a, b):
    return a * b / gcd(a, b)

def main():
    T, A, B = map(int, input().split())
    C = int(lcm(A, B))
    cnt1 = T // A - 1 if T % A == 0 else T // A
    cnt2 = T // B - 1 if T % B == 0 else T // B
    cnt3 = T // C - 1 if T % C == 0 else T // C
    print(cnt1 + cnt2 - cnt3 + 1)




if __name__ == "__main__":
    main()