/* -*- coding: utf-8 -*-
 *
 * 182.cc: No.182 新規性の虜 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100000;

/* typedef */

/* global variables */

int as[MAX_N];

/* subroutines */

/* main */

int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) cin >> as[i];
  sort(as, as + n);

  int cnt = 0, pa = 0, pc = 0;
  for (int i = 0; i < n; i++) {
    if (pa != as[i]) {
      if (pc == 1) cnt++;
      pc = 1;
    }
    else
      pc++;
    pa = as[i];
  }
  if (pc == 1) cnt++;

  printf("%d\n", cnt);
  return 0;
}