class DirectedGraph(): def __init__(self, N): self.N = N self.G = [[] for i in range(N)] self.rG = [[] for i in range(N)] self.order = [] self.used1 = [0] * N self.used2 = [0] * N self.group = [-1] * N self.label = 0 self.seen = [0] * N self.Edge = set() def add_edge(self, u, v): #多重辺は排除する if (u, v) not in self.Edge: self.G[u].append(v) self.rG[v].append(u) self.Edge.add((u, v)) def dfs(self, s): stack = [~s, s] while stack: u = stack.pop() if u >= 0: if self.used1[u]: continue self.used1[u] = 1 for v in self.G[u]: if self.used1[v]: continue stack.append(~v) stack.append(v) else: u = ~u if self.seen[u]: continue self.seen[u]= 1 self.order.append(u) def rdfs(self, s, num): stack = [s] while stack: u = stack.pop() if u >= 0: self.used2[u] = 1 self.group[u] = num for v in self.rG[u]: if self.used2[v]: continue stack.append(v) def scc(self): for i in range(self.N): if self.used1[i]: continue if i != 0: print("No") exit() self.dfs(i) for s in reversed(self.order): if self.used2[s]: continue self.rdfs(s, self.label) self.label += 1 return self.label, self.group def construct(self): nG = [set() for _ in range(self.label)] mem = [[] for i in range(self.label)] for s in range(self.N): now = self.group[s] for u in self.G[s]: if now == self.group[u]: continue nG[now].add(self.group[u]) mem[now].append(s) return nG, mem N = int(input()) G = DirectedGraph(N) for i in range(N): A = list(map(int, input().split())) M = A.pop(0) for j in range(M): G.add_edge(i, A[j]-1) G.scc() nG, mem = G.construct() if 0 not in mem[0]: print("No") exit() N = len(nG) dp = [-100] * N dp[0] = 0 for i in range(N): for v in nG[i]: dp[v] = max(dp[v], dp[i] + 1) print("Yes") if max(dp) == N-1 else print("No")