710 B | 710 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from datetime import datetime, timedelta
# sys.setrecursionlimit(10**7)
BLANK = " "
# inp = input
inp = lambda : sys.stdin.readline().rstrip()
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()
d = {}
for i in range(n):
a, b = inp().split()
if a == "ChongChong":
d[a] = True
if b == "ChongChong":
d[b] = True
if d.get(a, False) or d.get(b, False):
d[a] = d[b] = True
p(sum(d.values()))
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()