// g++ -std=c++11 temp.cpp
#include <bits/stdc++.h>
using namespace std;

#define FOR(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define REP(i,n) FOR(i,0,n)
#define EACH(itr,v) for(auto itr:v)
#define pb(s) push_back(s)
#define mp(a,b) make_pair(a,b)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;
typedef pair<P, int> PPI;

#define INF INT_MAX/3

#define MAX_N 1000

int n;
int w[100];
int sum = 0;
bool dp[11111];

int main(){
	cin>>n;
	REP(i,n){
		cin>>w[i];
		sum += w[i];
	}
	if(sum%2==1){
		cout<<"impossible"<<endl;
		return 0;
	}
	sum/=2;
	REP(i,11111) dp[i] = false;
	dp[0] = true;
	REP(i,n){
		REP(j,11111){
			if(dp[j]) dp[j+w[i]] = true;
		}
	}
	if(dp[sum]) cout<<"possible"<<endl;
	else cout<<"impossible"<<endl;

	return 0;
}