734 B | 734 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from datetime import datetime, timedelta
BLANK = " "
inp = input
# inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = BLANK : [*map(int,inp().split(x))]
mfi = lambda x = BLANK : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
n = ii()
k = ii()
l = [ii() for _ in range(k)]
cnt = [0] * (n + 1)
ans = 0
sm = 0
for i in l:
for j in range(i, n + 1, i):
cnt[j] = 1 - cnt[j]
if cnt[j] == 1:
sm += 1
else:
sm -= 1
ans = max(ans, sm)
p(ans)
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()