s = input()
N = len(s)
a, b, c = 0, 0, 0
for i in range(N):
    if s[i] == "a":
        a += 1
    elif s[i] == "b":
        b += 1
    else:
        c += 1

r = [a, b, c]
r = sorted(r, reverse=True)
if len(s) % 3 == 0 and len(s) // 3 >= r[0]:
    print("YES")
elif len(s) % 3 == 1 and len(s) // 3 + 1 >= r[0] and len(s) // 3 >= r[1]:
    print("YES")
elif len(s) % 3 == 2 and len(s) // 3 + 1 >= r[0] and len(s) // 3 + 1 >= r[1] and len(s) // 3 >= r[2]:
    print("YES")
else:
    print("NO")