forests.py

#!/usr/bin/env python3
# https://open.kattis.com/problems/forests
p,t=map(int,input().split())
x=[0]*p
while True:
    try:l=input()
    except:break
    if not l:break
    a,b=[int(k)-1 for k in l.split()]
    x[a]|=1<<b
print(len(set(x)))