N=int(input())

# UnionFind

Group = [i for i in range(20001)] # グループ分け
Nodes = [1]*(20001) # 各グループのノードの数

def find(x):
    while Group[x] != x:
        x=Group[x]
    return x

def Union(x,y):
    if find(x) != find(y):
        if Nodes[find(x)] < Nodes[find(y)]:
            
            Nodes[find(y)] += Nodes[find(x)]
            Nodes[find(x)] = 0
            Group[find(x)] = find(y)
            
        else:
            Nodes[find(x)] += Nodes[find(y)]
            Nodes[find(y)] = 0
            Group[find(y)] = find(x)

P=[list(map(int,input().split())) for i in range(N)]
for a,b,c,d in P:
    Union(a*110+b,c*110+d)

Point=[set() for i in range(20001)]
Edge=[0]*20001

for a,b,c,d in P:
    x=find(a*110+b)
    Edge[x]+=1
    Point[x].add(a*110+b)
    Point[x].add(c*110+d)

for i in range(20001):
    if len(Point[i])+1<=Edge[i]:
        print("NO")
        exit()

print("YES")