S = input()
N = len(S)
dp = [[0 for _ in range(27)] for _ in range(4)]
dp[0][0] = 1
for i in range(N):
    ndp = [[0 for _ in range(27)] for _ in range(4)]
    for j in range(4):
        for k in range(27):
            if dp[j][k]==0:
                continue
            ndp[j][k] += dp[j][k]
            nk = ord(S[i]) - ord('A') + 1
            if j==0:
                ndp[j+1][nk] += dp[j][k]
            elif j==1:
                if k==nk:
                    ndp[j+1][nk] += dp[j][k]
            elif j==2:
                if k!=nk:
                    ndp[j+1][nk] += dp[j][k]

    dp = ndp
ans = sum(dp[3])
print(ans)