void ranks(const string &v, map<char, int> &m){
          for(int i=0; i<v.size(); ++i) {
                  m[v[i]] = -1;
          }
          int c=0;
          for(map<char, int>::iterator it = m.begin(); it != m.end(); it++) {
                        it->second = c++;              
          }
}
int winner(vector<string> votes) {
    vector<int> rankings (votes[0].size(), 0);
    for(int i=0; i<votes.size(); ++i) {
            map<char, int> r;
            ranks(votes[i], r);
            for(int j = 0; votes[i].size(); ++j) {
                            rankings[j] += r[votes[i][j]];
            }
    }
    
    int winner_index = min(rankings.begin(), rankings.end()) - rankings.begin();
    int winner_val =  rankings[winner_index];
    
    int c_rep = 0;
    
    for(int i=0; i<rankings.size(); i++) {
            c_rep += winner_val == rankings[i];        
    }
    
    if (c_rep > 1) return -1;
    
    return winner_index;
}