#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define all(x) (x).begin(),(x).end()
const int mod=1000000007,MAX=100001,INF=1<<30;

int main(){

    int N;cin>>N;
    vector<int> A(N);
    int sum=0;
    for(int i=0;i<N;i++){
        cin>>A[i];
        sum+=A[i];
    }
    
    if(sum%2==1) cout<<"impossible"<<endl;
    else{
        bool dp[N+1][sum+1];
        for(int i=0;i<N+1;i++){
            for(int j=0;j<sum+1;j++){
                dp[i][j]=0;
            }
        }
        dp[0][0]=1;
        
        for(int i=0;i<N;i++){
            for(int j=sum;j>=0;j--){
                bool ok=0;
                if(j-A[i]>=0&&dp[i][j-A[i]]) ok=1;
                if(dp[i][j]) ok=1;
                if(ok) dp[i+1][j]=1;
                else dp[i+1][j]=0;
            }
        }
        
        if(dp[N][sum/2]) cout<<"possible"<<endl;
        else cout<<"impossible"<<endl;
    }
    
}