from collections import defaultdict
import sys
input = sys.stdin.readline
N = int(input())
ST = [input().split() for _ in range(N)]
S = defaultdict(int)
for s, t in ST:
    S[s] += 1
    S[t] += 1
flag = True
for s, t in ST:
    if S[s]==1 or S[t]==1:
        continue
    flag = False
    break
if flag:
    print("Yes")
else:
    print("No")