#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
const int N = 10000;
int x , k, m, n , t ; 
bool falg = true;
vector<int> a;
int main()
{
	cin >> n;
	while(falg)
	{
		int x;
     	scanf("%d" , &x) ;
		if (cin.get() == '\n')
		{
			t++;
			if (t == n)
			{
				a.push_back(x);
			
				sort(a.begin(), a.end());
				for (int i = 0; i < a.size() - 1; i++)
				{
					if (a[i] + 1 != a[i + 1] && a[i]!= a[i + 1])
					{
						cout << a[i] + 1 << " "; //缺数
					}
					if (a[i] == a[i + 1])
					{
						cout << a[i+1] << endl; // 重复
					}
				  }
				  falg = false ; 
			return 0;
			}
		}
		a.push_back(x);
		

	}
	
}