#include <iostream>
#include <iomanip>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <list>
#include <string>
#define _USE_MATH_DEFINES
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <bitset>
#define REP(i,n) for(int (i)=0;(i)<(n);(i)++)
#define RREP(i,n) for(int (i)=(n)-1;(i)>=0;(i)--)
#define debug(x) cout<<x<<endl
using namespace std;
typedef pair<int,int> P;
typedef priority_queue<int> maxpq;
typedef priority_queue<int,vector<int>,greater<int> > minpq;
typedef priority_queue<P> p_maxpq;
typedef priority_queue<P,vector<P>,greater<P> > p_minpq;
typedef vector<int> veci;
typedef vector<P> vecp;
typedef vector<string> vecs;
typedef long long int LL;
#define INF 2000000000
struct edge{int to,cost;};

int main(void) {
	int N;cin>>N;
	int W[100];
	REP(i,N) cin >> W[i];
	sort(W,W+N);
	int weight = 0;
	REP(i,N) weight += W[i];
	if(weight%2==1) {
		cout <<"impossible"<<endl;
		return 0;
	}
	bool dp[100][10000] = {0};
	dp[0][W[0]] = true;
	REP(i,N-1) {
		dp[i][0] = true;
		for(int j = 0;j <= weight/2;j++) {
			if(dp[i][j-W[i+1]]) dp[i+1][j] = true;
		}
	}
	if(dp[N-1][weight/2]) cout <<"possible"<<endl;
	else cout<<"impossible"<<endl;
	return 0;
}