import java.io.*;

class Main{
public static void main(String[] args) throws IOException{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
String line="";
while((line=br.readLine())!=null){
int n=Integer.parseInt(line);
int[] w=new int[n];
int[] dp=new int[10001];
dp[0]=1;
int total=0;
String[] values=br.readLine().split(" ");
for(int i=0;i<n;i++){
w[i]=Integer.parseInt(values[i]);
for(int j=10000;j>=0;j--){
if(dp[j]==1){
dp[j+w[i]]=1;
}
}
total+=w[i];
}
if(total%2==1){
System.out.println("impossible");
continue;
}
total/=2;
System.out.println(dp[total]==1?"possible":"impossible");
}
}
}