def solve():
    from collections import defaultdict

    N = int(input())
    S = [None] * N; T = [None] * N
    D = defaultdict(int)
    for i in range(N):
        S[i], T[i] = input().split()
        D[S[i]] += 1
        D[T[i]] += 1

    return all(D[S[i]] == 1 or D[T[i]] == 1 for i in range(N))

#==================================================
print("Yes" if solve() else "No")