#include<bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
using namespace std;
#define pb push_back
int dy[]={0, 0, 1, -1, 1, 1, -1, -1};
int dx[]={1, -1, 0, 0, 1, -1, -1, 1};

#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define mp make_pair
#define fi first
#define sc second
#define INF 1000000000
ll n;
ll dp[200][30000];

ll p[200];

int main(){
	cin >> n;
	REP(i,n)
		cin >> p[i];

	ll sum = 0;
	REP(i,n)
		sum += p[i];
	if(sum % 2 == 1){
		cout << "impossible" << endl;
		return 0;
	}
	sum /= 2;

	REP(i,sum + 1){
		dp[0][i] = (i == p[0]) ? 1 : -INF;
	}
	dp[0][0] = 0;

	FOR(i,1,n){
		REP(j,sum+1){
			if(j < p[i]){
				dp[i][j] = dp[i - 1][j];
				continue;
			}

			dp[i][j] = max(dp[i - 1][j - p[i]] + 1,dp[i - 1][j]);
		}
	}

	cout << ((dp[n - 1][sum] > 0) ? "possible" : "impossible") << endl;
	return 0;

}