//inlclude前用define 
#define _USE_MATH_DEFINES

//include
#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<cmath>

using namespace std;
//typedef
typedef vector<int> VI;
typedef vector<string> VS;
typedef vector<char> VC;

int main() {
	int n;
	cin >> n;
	VI a(n);
	for (int i = 0; i < n; i++) cin >> a[i];
	sort(a.begin(), a.end());
	int memo = a[0],cnt=0;
	bool sinki = true;
	for (int i = 1; i < n; i++) {
		if (memo == a[i]) {
			sinki = false;
		} else {
			memo = a[i];
			if (sinki) {
				cnt++;
			}
			sinki = true;
		}
	}
	cout << cnt << endl;
	return 0;
}