#include <stdio.h>
int n,w[100],dp[100][10000];

int main(void){
   scanf("%d",&n);
   int i,j,x=0;
   for(i=0;i<n;i++){
       scanf("%d",&w[i]);
       x+=w[i];
   }
   dp[n][0]=1;
   for(i=n-1;i>=0;i--){
       for(j=0;j<10000;j++){
           dp[i][j]=dp[i+1][j]>dp[i+1][j+2*w[i]]?dp[i+1][j]:dp[i+1][j+2*w[i]];
       }
   }
   puts(dp[0][x]?"possible":"impossible");
}