s = input()
cnt_a = 0
cnt_b = 0
cnt_c = 0
for i in s:
    if i == "a":
        cnt_a += 1
    elif i == "b":
        cnt_b += 1
    else:
        cnt_c += 1
if max(cnt_a, cnt_b, cnt_c) - min(cnt_a, cnt_b, cnt_c) <= 1:
    print("YES")
else:
   print("NO")