n=int(input())
s={}
g=[input().split() for _ in range(n)]

for i,j in g:
  s[i]=s.get(i,0)+1
  s[j]=s.get(j,0)+1
  
for i,j in g:
  if s[i]==1 or s[j]==1:
    continue
  else:
    print('No')
    exit()
    
print('Yes')