#include <bits/stdc++.h>
using namespace std;

#define int long long

#define rep(i,s,n) for(int i = s;i<n;i++)
#define repe(i,s,n) for(int i = s;i<=n;i++)
#define rrep(i,s,n) for(int i = (n)-1;i>=(s);i--)
#define all(v) (v).begin(),(v).end()
#define pb push_back
#define fi first
#define se second
#define chmin(a,b) a=min((a),(b))
#define chmax(a,b) a=max((a),(b))
typedef long long ll;
typedef pair<int,int>pint;
typedef vector<int>vint;
typedef vector<pint>vpint;
typedef pair<pint,int> P1;
typedef pair<int,pint> P2;
typedef pair<pint,pint>PP;
static const ll maxLL = (ll)1 << 62;
const ll MOD=1000000007;
const ll INF=1e18;
int dx[]={0,0,1,-1};
int dy[]={-1,1,0,0};

int N;
int a[100010];
int dp[100010];

signed main(){
    cin.tie(0);
	ios::sync_with_stdio(false);
    cin>>N;
    int sum=0;
    rep(i,0,N){
        cin>>a[i];
        sum+=a[i];
    }
    if(sum%2){
        cout<<"impossible"<<endl;
        return 0;
    }
    sort(a,a+N);
    memset(dp,-1,sizeof(dp));
    dp[0]=0;
    rep(i,0,N)rrep(j,0,sum/2+1){
        if(j>=a[i] && dp[j-a[i]]==0){
            dp[j]=dp[j-a[i]];
        }
    }
    //cout<<sum/2<<endl;
    if(dp[sum/2]==0)cout<<"possible"<<endl;
    else cout<<"impossible"<<endl;
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    return 0;
}