n=int(input())
z=['']*100
z[28]='A'
z[39]='B'
z[79]='C'
for i in range(n):
	*a,=input().split()
	p=int(a[0]+a[1])
	f=int(a[2]+a[3])
	z[f],z[p]=z[p],''
print('YNEOS'[z[58]+z[48]+z[68]!='ABC'::2])