void deDup(string &str) {
    sort(str.begin(), str.end()); 
    auto last = std::unique(str.begin(), str.end()); 
    str.erase(last, str.end()); 
}

int gemstones(vector<string> arr) {
    map<char, int> aparitions;
    
    for(int i=0; i<arr.size(); i++){
        deDup(arr[i]);
        for(int j=0; j<arr[i].size(); j++){
            aparitions[arr[i][j]] += 1; 
        }
    }
    
    int rocks = 0;
    for (auto& pair : aparitions){
        if(pair.second==arr.size()){
            rocks++;
        }
    }
    
    return rocks;
}