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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<ll, ll>;
using Pld = pair<ld, ld>;
using Vec = vector<ll>;
using VecP = vector<P>;
using VecB = vector<bool>;
using VecC = vector<char>;
using VecD = vector<ld>;
using VecS = vector<string>;
using Graph = vector<VecP>;
#define REP(i, m, n) for(ll (i) = (m); (i) < (n); ++(i))
#define REPR(i, m, n) for(ll (i) = (m); (i) > (n); --(i))
#define rep(i, n) REP(i, 0, n)
#define R cin>>
#define repr(i, n) REPR(i, n, 0)
#define all(s) (s).begin(), (s).end()
#define pb push_back
#define mp make_pair
#define fs first
#define sc second
#define in(a) insert(a)
#define P(p) cout<<(p)<<endl;
#define ALL(x) (x).begin(),(x).end()
#define ALLR(x) (x).rbegin(),(x).rend()
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<long long int> vll;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;
typedef pair<ll, ll> pll;
void sonic(){ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);}
void setp(const ll n){cout << fixed << setprecision(n);}
const ll INF = 1e9+1;
const ll LINF = 1e18+1;
const ll MOD = 1e9+7;
//const ll MOD = 998244353;
const ld PI = acos(-1);
const ld EPS = 1e-11;
template<typename T> void co(T e){cout << e << "\n";}
template<typename T> void co(const vector<T>& v){for(const auto& e : v)
{ cout << e << " "; } cout << "\n";}
ll gcd(ll a, ll b) {
    if (a < b)swap(a, b);
    if (b == 0) return a;
    unsigned r;
    while ((r = a % b)) {
        a = b;
        b = r;
    }
    return b;
}
ll lcm(ll a, ll b) {
    ll g = gcd(a, b);
    return a * b / g;
}
bool prime(ll n) {
    for (ll i = 2; i <= sqrt(n); i++) {
        if (n%i == 0)return false;
    }
    return n != 1;
}

Vec fac, finv;

ll PowMod(ll a, ll n){
    if(n == 1) return a;
    if(n%2 == 0) return PowMod(a*a%MOD, n/2);
    return a*PowMod(a*a%MOD, n/2)%MOD;
}

ll combi(ll n, ll k){
    if(k>n) return 0;
    return fac[n]*finv[k]%MOD*finv[n-k]%MOD;
}

int main(){
    int n, m, ans=0;
    cin>>n>>m;
    Vec v(n);
    rep(i,n){
        int k;
        cin>>k;
        while(k--){
            int a;
            cin>>a;
            v[a - 1]++;
        }
    }
    rep(i,m) if(v[i]==n) ans++;
    co(ans);
}