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class Solution {
public:
    string convertToTitle(int n) {
        string title = "";
        while (n > 0)
        {
                title += 'A' + n % 26 - 1;
                n /= 26;
        }
        int pos0 = 0;
        while (pos0 < title.length())
        {
            int pos = pos0;
            while (title[pos] == '@' && pos < title.length())
            {
                title[pos] = 'Z';
                if (pos + 1 < title.length() && title[pos + 1] != '@')
                {
                    title[pos+1]--;
                    pos++;
                }
                else
                {
                    title = title.substr(0, pos);
                    break;
                }
            }
            pos0++;
        }
        int s = 0;
        int e = title.length() - 1;
        while (s < e)
        {
            char tmp = title[s];
            title[s] = title[e];
            title[e] = tmp;
            s++;
            e--;
        }
        return title;
    }
};