import collections,sys,math,functools,operator,itertools,bisect,heapq,decimal,string,time,random #https://github.com/shakayami/ACL-for-python/blob/master/two_sat.py def two_sat(n,clause): answer=[0]*n edges=[] N=2*n for s in clause: i,f,j,g=s edges.append((2*i+(0 if f else 1),2*j+(1 if g else 0))) edges.append((2*j+(0 if g else 1),2*i+(1 if f else 0))) M=len(edges) start=[0]*(N+1) elist=[0]*M for e in edges: start[e[0]+1]+=1 for i in range(1,N+1): start[i]+=start[i-1] counter=start[:] for e in edges: elist[counter[e[0]]]=e[1] counter[e[0]]+=1 visited=[] low=[0]*N Ord=[-1]*N ids=[0]*N NG=[0,0] def dfs(v): stack=[(v,-1,0),(v,-1,1)] while stack: v,bef,t=stack.pop() if t: if bef!=-1 and Ord[v]!=-1: low[bef]=min(low[bef],Ord[v]) stack.pop() continue low[v]=NG[0] Ord[v]=NG[0] NG[0]+=1 visited.append(v) for i in range(start[v],start[v+1]): to=elist[i] if Ord[to]==-1: stack.append((to,v,0)) stack.append((to,v,1)) else: low[v]=min(low[v],Ord[to]) else: if low[v]==Ord[v]: while(True): u=visited.pop() Ord[u]=N ids[u]=NG[1] if u==v: break NG[1]+=1 low[bef]=min(low[bef],low[v]) for i in range(N): if Ord[i]==-1: dfs(i) for i in range(N): ids[i]=NG[1]-1-ids[i] for i in range(n): if ids[2*i]==ids[2*i+1]: return None answer[i]=(ids[2*i]<ids[2*i+1]) return answer #sys.setrecursionlimit(10**9) #sys.set_int_max_str_digits(0) input = sys.stdin.readline n = int(input()) #alist = list(map(int,input().split())) #alist = [] #s = input() #n,m = map(int,input().split()) #for i in range(n): # alist.append(list(map(int,input().split()))) co = collections.defaultdict(list) x = 1 << 30 for i in range(n): a,b,c = map(int,input().split()) co[a*x+b].append(i) co[b*x+c].append(i) co[a*x+c].append(~i) cl = [] for i in co: if len(co[i]) >= 3: exit(print('NO')) if len(co[i]) == 2: z = 0 if co[i][0] < 0: co[i][0] = ~co[i][0] z ^= 1 if co[i][1] < 0: co[i][1] = ~co[i][1] z ^= 1 if z == 1: cl.append((co[i][0],True,co[i][1],False)) cl.append((co[i][0],False,co[i][1],True)) else: cl.append((co[i][0],True,co[i][1],True)) cl.append((co[i][0],False,co[i][1],False)) ans = two_sat(n,cl) if ans != None: print('YES') else: print('NO')