def same_frequencies(s):
letters = [0] * 256
lenn = len(s)
for i in range(lenn):
if (s[i].isalpha()):
letters[ord(s[i]) - ord('a')] += 1
frequencies = 0
for i in range(256):
if (letters[i] != 0):
frequencies = letters[i]
break
for i in range(256):
if (letters[i] != 0 and (letters[i] != frequencies)):
return False
return True
s = "aaabbbcccwww"
if (same_frequencies(s)):
print("yes")
else:
print("no")