#include <bits/stdc++.h>
using namespace std;
 
int n,a[100100],x;
int main() {
    cin>>n;
    for(int i = 1;i <= n;i++){
        cin>>x;
        a[x]++;
    }
     
    for(int i = 1;i <= n;i++){
        if(a[i] == 0) cout<<i<<" ";
    }
}
/**************************************************************
	Problem: 2029
	User: zhengyuxuan
	Language: C++
	Result: Accepted
	Time:60 ms
	Memory:2464 kb
****************************************************************/