import sys
import collections
S = input()
count_dict = collections.Counter(S)
Num_A = count_dict["a"]
Num_B = count_dict["b"]
Num_C = count_dict["c"]

judge = sorted([Num_A, Num_B, Num_C])
if judge[2]-judge[0]>1:
    print('NO')
else:
    print('YES')