#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <map>
#include <queue>
#include <numeric>
#include <climits>
#include <iterator>
#include <bitset>
#include <functional>
using namespace std;
const constexpr int INF = 1e9;
typedef std::pair<std::string,double> P;

int L, N, sum; 
vector<int> v;
int dist[10001];
bool dp[10000+10];
void solve(){
    for(int i=0; i<N; ++i){
        int a; cin >> a; v.push_back(a);
        sum += a;
    }
    if(sum%2!=0){
        cout << "impossible" << endl;
        return ;
    }
    for(int i=0; i<10010; ++i) dp[i]=false;
    dp[0]=true;
    dp[sum]=true;
    
    for(int i=sum/2; i>=0; --i){
        for(int j=0; j<N; ++j){
            if(i-v[j]>0){
                dp[i-v[j]] |= dp[i];
            }
        }
    }
    if(dp[sum/2]) cout << "possible" << endl;
    else cout << "impossible" << endl;
}
int main() {
    cin >> N;
    solve();
	return 0;
}