def shortPalindrome(s):
    charCount = {}
    pairCount = {}
    pairHash = {}
    totalCount = 0
    MOD = 10**9 + 7

    for char in s:
        charIndex = ord(char) - ord('a')
        pairIndex = charIndex
        totalCount = (totalCount + pairCount.get(charIndex, 0)) % MOD

        for pairChar in range(26):
            pairCount[pairChar] = (pairCount.get(pairChar, 0) + pairHash.get(pairIndex, 0)) % MOD
            pairHash[pairIndex] = (pairHash.get(pairIndex, 0) + charCount.get(pairChar, 0)) % MOD
            pairIndex += 26

        charCount[charIndex] = charCount.get(charIndex, 0) + 1

    return totalCount