def gemstones(arr):
    s = set(arr.pop())
    for string in arr:
        s = s.intersection(string)
    return len(s)

import reduce from functools

def gemstones(arr):
    sarr = list(map(set, arr))
    return len(reduce(lambda c, f: c.intersection(f), sarr))

int gemstones(vector<string> arr) {
    int result = 0;
    string liste = "abcdefghijklmnopqrstuvwxyz";
    for(int j = 0; j < liste.size(); j++){
        int cp = 0;
        for(int i = 0; i < arr.size(); i++){
            if(arr[i].find(liste[j]) != string::npos) cp++;
        }
        if(cp == arr.size())result++;
    }
    return result;
}

string getShortest(vector<string> arr) {
    string result = arr[0];
    for(int i = 1; i < arr.size(); i++){
        if(arr[i].size() < result.size()) result = arr[i];
    }
    return result;
}
int gemstones(vector<string> arr) {
    int result = 0;
    string shortest = getShortest(arr);
    set<char> liste(shortest.begin(), shortest.end());
    for(auto j = liste.begin(); j != liste.end(); j++){
        int cp = 0;
        for(int i = 0; i < arr.size(); i++){
            if(arr[i].find(*j) != string::npos) cp++;
        }
        if(cp == arr.size())result++;
    }
    return result;
}

def gemstones(arr):    
    dict_ans = {}
    counter = 0
    for i in arr:
        for j in set(i):
            dict_ans[j] = (dict_ans.get(j) or 0) + 1
            if dict_ans[j] == len(arr):
                counter += 1
    return counter

function gemstones(arr) {
    // Write your code here
    let count=0;
    let minerals=""
    let str=arr.join("");
    
    for(let i of str){
        if(!minerals.includes(i)){
             minerals+=i
        }
    }
    
    for (let i of minerals){
        let skip=false
        for(let j of arr){
            if(!j.includes(i)){
                skip=true
                break;
            }  
        }
        if(skip==false){
            count++  
        }
    }
    return count
}