from collections import defaultdict

N = int(input())
ST = [list(input().split()) for _ in range(N)]

D = defaultdict(int)
for S, T in ST:
    D[S] += 1
    D[T] += 1
for S, T in ST:
    D[S] -= 1
    D[T] -= 1
    if 1 <= min(D[S], D[T]):
        print("No")
        break
    D[S] += 1
    D[T] += 1
else:
    print("Yes")