Annapoorna

from itertools import combinations

def min_menu_items(n, preferences):
customers = list(preferences.values())

for r in range(1, n + 1):
for combo in combinations(range(n), r):
if all(any(item in combo for item in customer) for customer in customers):
return len(combo), list(combo)
return -1, []

n = int(input())
t = int(input())
preferences = dict()
for i in range(0,t):
preferences[i] = eval(input())

count, items = min_menu_items(n, preferences)
print(count)