cp2019_zad1

#include <iostream>
#include <string>
#include <string.h>
#include <stdio.h>

#define DEBUG
#ifdef DEBUG
#define print(var) cout << #var << ": " << var << endl;
#else
#define print(var) ;
#endif // DEBUG

#define cig cin.ignore();

using namespace std;

string solve(string num1, string num2 = "0123456789") {
    string result;

    for (int n = 0; n < 10; n++) {
        if (num1.find_first_of('0' + n) != -1 && num2.find_first_of('0' + n) != -1) {
            result += '0' + n;
            //print(result);
        }
    }

    return result;
}

int main() {

    int n;

    while (cin >> n) {
        cig;

        string currentNumber;
        cin >> currentNumber;
        currentNumber = solve(currentNumber);


        for (int i = 1; i < n; i++) {
            string newNumber;
            cin >> newNumber;
            currentNumber = solve(currentNumber, newNumber);
        }

        cout << currentNumber.length() << endl;
    }
}