from sys import stdin,setrecursionlimit#,set_int_max_str_digits
#import pypyjit
#pypyjit.set_param('max_unroll_recursion=-1')
#setrecursionlimit(250000) # これこどふぉだと無理
#set_int_max_str_digits(200010)
mod = 998244353 
ii = lambda :int(stdin.readline())
mi = lambda :map(int,stdin.readline().split())
li = lambda :list(mi())
gmi = lambda :map(lambda x: int(x) - 1, stdin.readline().split())
gi = lambda :list(map(lambda x: -1 if x == "." else 1,input())) # グリッド入力受け取り
py = lambda :print("Yes")
pn = lambda :print("No")
pf = lambda :print("First") 
ps = lambda :print("Second")
vec = [(1,0),(-1,0),(0,-1),(0,1)]
vec1 = [(1,0),(1,1),(0,1),(-1,1),(-1,0),(-1,-1),(0,-1),(1,-1)] #8方向
vec2 = [(1,1),(1,0),(0,-1),(-1,-1),(-1,0),(0,1)] # 六角形グリッド
inf = 2*10**18
from collections import defaultdict,deque
from heapq import heappop,heappush


n = ii()
cnt = defaultdict(int) 
cnt1 = defaultdict(int) 

data = [input().split() for _ in range(n)]

for s,t in data:
    cnt[s] += 1 
    cnt1[t] += 1 

for s,t in data:
    if min(cnt[s],cnt1[t]) == 1:
        continue 
    pn()
    exit()

py()