from math import gcd
def lcm(x, y):
    return x*y // gcd(x, y)

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

a = (T-1) // A
b = (T-1) // B

l = lcm(A, B)
c = (T-1)//l
ans = a + b - c + 1
print(ans)