import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
sys.setrecursionlimit(10 ** 7)

from math import gcd

t, a, b = map(int, readline().split())
t -= 1
print(t // a + t // b - t // (a * b // gcd(a, b)) + 1)