#include <cmath>
#include <cstdio>
#include <iostream>

#include <vector>
#include <set>
#include <algorithm>

using namespace std;

int intersect_sz(const vector<int> &a,const vector<int> &b);

// Poner a 1 para imprimir los vectores por pantalla
int DUMP=0;

int dumpv(const vector<int> &a,const char *s=NULL) {
  int N=a.size();
  if (s) printf("%s: ",s);
  for (int j=0; j<N; j++)
    printf("%d ",a[j]);
  if (s) printf("\n");
}

int main() {
  int N=20, M=2*N;
  vector<int> a(N),b(N);
  srand(19400310);
  for (int j=0; j<N; j++) {
    a[j]=rand()%M;
    b[j]=rand()%M;
  }
  if (DUMP) {
    dumpv(a,"a"); 
    dumpv(b,"b"); 
  }
  int count = intersect_sz(a,b);
  cout << count << endl;
  return 0;
}

//================================================================
//  PARTICIPANTES DEL TORNEO SOLO DEBERIAN MODIFICAR
//  DE AQUI PARA ABAJO
//================================================================

int contains(const vector<int> &a,int x) {
  int N=a.size();
  for (int j=0; j<N; j++) 
    if (a[j]==x) return 1;
  return 0;
}

int intersect_sz(const vector<int> &a,
                 const vector<int> &b) {
  vector<int> c;
  int Na = a.size();
  int Nb = b.size();
  int count = 0;
  for (int ja=0; ja<Na; ja++) {
    int xa = a[ja];
    if (contains(b,xa) && !contains(c,xa)) {
      count++;
      c.push_back(xa);
    }
  }
  if (DUMP) {
    dumpv(c,"c"); 
  }
  return count;
}