s = input()[::-1]
n = len(s)
a = [ord(s[i]) - ord("A") for i in range(n)]
dp = [[0] * 26 for i in range(2)]
ans = 0
for i in range(n):
	ndp = [[0] * 26 for i in range(2)]
	for j in range(2):
		for k in range(26):
			ndp[j][k] = dp[j][k]
	ndp[0][a[i]] += 1
	for j in range(26):
		if j == a[i]: continue
		ndp[1][a[i]] += dp[0][j]
	ans += dp[1][a[i]]
	dp[0] = ndp[0][::]
	dp[1] = ndp[1][::]

print(ans)