s = input()
a = len(s)
flag = 0
for i in range(0,a,2):
  if s[i]<='a' and s[i]>='z':
    flag = 1
    break
if flag==0:
  for j in range(1,a,2):
    if s[j]!=" ":
      flag = 1
      break
if flag==0:
  print("Yes")
else:
  print("No")