import sys
input = sys.stdin.readline

N=int(input())

ANS=[-1]*(10**5+5)
flag=1

for i in range(N):
    s,t=list(map(int,input().split()))

    if ANS[s]==-1:
        ANS[s]=t
    elif ANS[s]==t:
        pass
    else:
        flag=0
        break

if flag:
    print("Yes")
else:
    print("No")