import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################
from collections import defaultdict
 
class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n
 
    def find(self, x):
        if self.parents[x] < 0:
            return x
        else:
            self.parents[x] = self.find(self.parents[x])
            return self.parents[x]
 
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
 
        if x == y:
            return
 
        if self.parents[x] > self.parents[y]:
            x, y = y, x
 
        self.parents[x] += self.parents[y]
        self.parents[y] = x
 
    def size(self, x):
        return -self.parents[self.find(x)]
 
    def same(self, x, y):
        return self.find(x) == self.find(y)
 
    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]
 
    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]
 
    def group_count(self):
        return len(self.roots())
 
    def all_group_members(self):
        group_members = defaultdict(list)
        for member in range(self.n):
            group_members[self.find(member)].append(member)
        return group_members
 
    def __str__(self):
        return '\n'.join(f'{r}: {m}' for r, m in self.all_group_members().items())

def g(x, y):
    if x < y:
        return x * D + y, 0
    else:
        return y * D + x, 1

D = 10 ** 8 + 100
m = ni()
p = [na() for i in range(m)]

s = []
for i in range(m):
    for j in range(3):
        s.append(g(p[i][j], p[i][(j+1) % 3])[0])
dic = {x:i for i, x in enumerate(s)}

n = len(s)
f = [[] for i in range(n)]
uf = UnionFind(m * 2)
for i in range(m):
    for j in range(3):
        x, y = g(p[i][j], p[i][(j+1) % 3])
        f[dic[x]].append((i, y))

for i in range(n):
    if len(f[i]) > 2:
        NO()
        exit()
    elif len(f[i]) == 2:
        a, b = f[i][0], f[i][1]
        if a[1] == b[1]:
            uf.union(a[0], b[0] + m)
            uf.union(a[0] + m, b[0])
        else:
            uf.union(a[0], b[0])
            uf.union(a[0] + m, b[0] + m)

for i in range(m):
    if uf.same(i, i + m):
        NO()
        exit()
YES()