#include<bits/stdc++.h>
using namespace std;
int arr[200086];
int ans;
int main() {
	int n;
	cin >> n;
	for (int i = 1; i <= 2 * n; i++) {
		int x;
		scanf("%d", &x);
		arr[x]++;
	}
	for (int i = 0; i <= n; i++) {
		if (arr[i] >= 2)ans = ans + 2;
		else if (arr[i] == 1)ans++;
	}
	cout << ans;
	return 0;
}