from collections import defaultdict

dic = defaultdict(int)
S = input()
N = len(S)
ans = 0
tmp1 = 0
for i, s in enumerate(S):
    x = 0
    if s in dic:
        x = dic[s]
    tmp1 += (i - x + 1)
    ans += tmp1
    print(ans, tmp1)
    dic[s] = i + 1
ans *= 2
ans /= N * (N + 1)
print(ans)