#!/usr/bin/env python3
#coding:utf-8

import math
import string
import random
import heapq
from sys import stdin
# import numpy as np
# from matplotlib import pyplot as plt

def gcd(a,b):
	while b>0:
		t=a
		a=b
		b=t%b
	
	return a
def lcm(a,b):
	return a/gcd(a,b)*b
def main():
	read=stdin.readline

	#edit here!
	t,a,b=map(int,read().split())

	ans=(t-1)//a+(t-1)//b+1-(t-1)//lcm(a,b)
	print(int(ans))

if __name__ == '__main__':
	main()