#!/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 main():
	read=stdin.readline

	#edit here!
	t,a,b=map(int,read().split())
	ans=(t+a-2)//a+(t+b-2)//b+1-(t+math.lcm(a,b)-2)//math.lcm(a,b)
	print(ans)

if __name__ == '__main__':
	main()