#include <cstdio>
#include <algorithm>
#include <vector>
#include <cstring>
#include <numeric>
#include <cassert>
#include <cmath>
using namespace std;
typedef unsigned int uint;
typedef unsigned long long LL;

#define FOR(k,a,b) for(uint k(a); k < (b); ++k)
#define REP(k,a) for(uint k=0; k < (a); ++k)


int main (int argc, char** argv) {
#ifdef HOME
	freopen("in.txt","rb",stdin);
	freopen("out.txt","wb",stdout);
#endif
	int N,tmp;
	scanf("%d",&N);
	//assert(N>0 && N<=1e5);
	vector<bool> v(N);
	REP(i,N)
	{
		scanf("%d",&tmp);
		//assert((tmp==-1) || (tmp>0 && tmp<=N));
		if (tmp != 0)
		v[tmp-1]=1;
	}
	REP(i,N) if(!v[i])
	{
		printf("%d ",i+1);
	}
	printf("\n");
	return 0;
}