696 B | 696 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():
P, T = mii()
l = []
while 1:
try:
l.append(mii())
except:
break
k = [[] for _ in range(P)]
for a, b in l:
k[a - 1].append(b)
k = set([tuple(set(sorted(i))) for i in k])
p(len(k))
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()