# https://github.com/robe2222555/atcoder-lib/blob/main/template/python/main.py
import sys
input = lambda: sys.stdin.readline().rstrip()
def LI(): return list(map(int, input().split()))
def II(): return int(input())


INF = 1<<60
def solve():
	N,A,B = LI()
	ans = 0
	for i in range(N+1):
		if i%A > i%B: ans += 1
	print(ans)
	return


def main():
	T = 1
	for _ in range(T):
		solve()
	return


if __name__ == '__main__':
	main()