import re
l = list(re.findall(r"[c,e,k,n,y,]", input()))

flg=0
if not(1<=l.count('k') and l.count('k')<=2):
    print("NO")
    flg=1
if not(3<=l.count('e') and l.count('k')<=4):
    print("NO")
    flg=1
if not(1<=l.count('y') and l.count('k')<=2):
    print("NO")
    flg=1
if not(1<=l.count('n') and l.count('k')<=2):
    print("NO")
    flg=1
if not(1<=l.count('c') and l.count('k')<=2):
    print("NO")
    flg=1
if flg<1:
  print("YES")