#include <iostream>
using namespace std;
int N,w[101],bit[101];
bool check(){
        int left,right;
        left=right=0;
        for(int i=0 ; i<N ; i++ ){
                if(bit[i]==0)
                        left+=w[i];
                else
                        right+=w[i];
        }
        return left==right;
}
bool recursion(int now){
        bool response=false;
        if(now==N){
                return check();
        }else{
                for(int i=0 ; i<2 ; i++ ){
                        bit[now]=i;
                        response|=recursion(now+1);
                }
        }
        return response;
}
int main(){
        cin >> N;
        for(int i=0 ; i<N ; i++ ){
                cin >> w[i];
        }
        if(recursion(0))
                cout<<"possible"<<endl;
        else    cout<<"impossible"<<endl;
        return 0;
}