MOD = 10 ** 9 + 7
INF = 10 ** 10
import sys
sys.setrecursionlimit(100000000)
dy = (-1,0,1,0)
dx = (0,1,0,-1)
from math import gcd

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

def main():
    t,a,b = map(int,input().split())
    t -= 1
    g = lcm(a,b)
    ans = t//a + t//b - t//g + 1
    print(ans)
if __name__ =='__main__':
    main()