import heapq
from collections import defaultdict

N = int(input())

Edge = defaultdict(list)

for _ in range(N-1):
    v, u = map(int, input().split())
    Edge[v-1].append(u-1)
    Edge[u-1].append(v-1)
    
S = [k for k, v in Edge.items() if len(v) == 1]

def dijkstra(s, i):
    global N, P, S
    D = [float('inf')] * N
    D[s] = 0
    q = [(0, s)]
    heapq.heapify(q)
    while len(q) > 0:
        cost, c = heapq.heappop(q)
        if cost > D[c]:
            continue
        for p in Edge[c]:
            if D[p] > D[c] + 1:
                D[p] = D[c] + 1
                heapq.heappush(q, (D[p], p))
    
    res = -1
    for e in S[i+1:]:
        if res < 0:
            res = D[e]
        elif res != D[e]:
            return -1
    return res

res = -1
for i, s in enumerate(S[:-1]):
    v = dijkstra(s, i)
    if v < 0:
        print('No')
        break
    elif res < 0:
        res = v
    elif res != v:
        print('No')
        break
else:
    print('Yes')