#yukicoder contest 473 第1回 生成AI作問コンテスト

'''
#A
S = input().split()
print(''.join(Si[0].upper() for Si in S))
'''

#B
N = int(input())
names = [input().split() for _ in range(N)]

#この問題AtCoderで見たな･･･？　名前を座標圧縮
S = []
for Si, Ti in names:
    S.append(Si)
    S.append(Ti)
back = None
S = [back := Si for Si in sorted(S) if back != Si]
import bisect
names = [(bisect.bisect_left(S, Si), bisect.bisect_left(S, Ti)) for Si, Ti in names]
n = len(S)

C = [0] * n
for Si, Ti in names:
    C[Si] += 1
    C[Ti] += 1
print('Yes' if all(C[Si] == 1 or C[Ti] == 1 for Si, Ti in names) else 'No')