#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> P;
ll n;
ll a[105];
bool dp[105][5005];
ll sum;
int main(void){
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>a[i];
        sum+=a[i];
    }
    if(sum%2==1){
        cout<<"impossible"<<endl;
        return 0;
    }
    dp[0][0]=true;
    dp[0][a[0]]=true;
    for(int i=1;i<n;i++){
        for(int j=0;j<=5000;j++){
            if(j-a[i]>=0&&dp[i-1][j-a[i]]==true) dp[i][j]=true;
            if(dp[i-1][j]==true) dp[i][j]=true;
        }
    }
    if(dp[n-1][sum/2]==true){
        cout<<"possible"<<endl;
    }else{
        cout<<"impossible"<<endl;
    }
    
}