int theLoveLetterMystery(string s) {
    int modifs = 0, lft = 0, rgt = s.size()-1;  
    
    while (lft<rgt) {
        int indx = s[lft]<=s[rgt]? rgt : lft; 
        
        while (s[lft]!=s[rgt]) {
            s[indx]--;
            modifs++;
        }
        
        lft++;
        rgt--;
    }
    return modifs;
}