Problem:
Score : 200 points

Problem Statement

Katsusando loves omelette rice.

Besides, he loves crème brûlée, tenderloin steak and so on, and believes that these foods are all loved by everyone.

To prove that hypothesis, he conducted a survey on M kinds of foods and asked N people whether they like these foods or not.

The i-th person answered that he/she only likes the A_{i1}-th, A_{i2}-th, ..., A_{iK_i}-th food.

Find the number of the foods liked by all the N people.

Constraints

All values in input are integers.

1 \leq N, M \leq 30

1 \leq K_i \leq M

1 \leq A_{ij} \leq M

For each i (1 \leq i \leq N), A_{i1}, A_{i2}, ..., A_{iK_i} are distinct.

Constraints

Input is given from Standard Input in the following format:

N M
K_1 A_{11} A_{12} ... A_{1K_1}
K_2 A_{21} A_{22} ... A_{2K_2}
:
K_N A_{N1} A_{N2} ... A_{NK_N}

Output

Print the number of the foods liked by all the N people.

Sample Input 1

3 4
2 1 3
3 1 2 3
2 3 2

Sample Output 1

1

As only the third food is liked by all the three people, 1 should be printed.

Sample Input 2

5 5
4 2 3 4 5
4 1 3 4 5
4 1 2 4 5
4 1 2 3 5
4 1 2 3 4

Sample Output 2

0

Katsusando's hypothesis turned out to be wrong.

Sample Input 3

1 30
3 5 10 30

Sample Output 3

3

Solution in C++ (GCC 9.2.1) (judge verdict: Accepted)

//include
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <cmath> 
#include <iomanip>
#include <math.h>
#include <utility>
#include <functional>
#include <cstdlib>
//using
using namespace std;
using vl = vector <long long>;
using vs = vector <string>;
using vc = vector <char>;
using ll= long long;
using vvl = vector<vector<ll> >;
//vector<vector<char> > hyou(N, vector<char>(N));
using vd = vector <double>;
//define
//#define int long long
#define rep(i,n) for(int i=0; i<n; i++)
#define print(n) cout<<n<<endl;
#define sortp(d) sort(d.begin(),d.end()) //1234
#define sortm(d) sort(d.rbegin(),d.rend()) //4321
//素数判定　O(√A) 
bool is_prime(int x){
 if(x<=1) return false;
 for(int i=2;i*i<=x;i++)
 if(x%i==0) return false;
 return true;
 }
/*順列生成
do {
  // 順列に対する処理
} while (next_permutation(配列変数.begin(), 配列変数.end()));*/

//絶対値　abs()
//文字→数字　'0' アルファベット→数字　'a'　'A'が65番,'a'が97番だわ
//型キャスト　char('a'+1)

//グローバル変数宣言
ll p=0,q=0,r=0;

int main()
{
  ll n,m;
  cin>>n>>m;
  vl k(n),l(m);
  vvl a(n,vl(m));

  rep(i,n){
    cin>>k[i];
    rep(j,k[i]){
      cin>>a[i][j];
      l[a[i][j]-1]++;
    }
  }

  rep(i,m)if(l[i]==n)p++;
  print(p);

}