from collections import defaultdict


def solve():
    N = int(input())
    all_names = defaultdict(int)

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

    for s, t in names:
        all_names[s] += 1
        all_names[t] += 1

    for s, t in names:
        if [s, t].count(s) == all_names[s]:
            continue
        elif [s, t].count(t) == all_names[t]:
            continue
        else:
            print("No")
            exit()

    print("Yes")


if __name__ == "__main__":
    solve()