#include <stdio.h>
int cmp(const void* a, const void* b){
  return *(int*)a - *(int*)b;
}
_Bool check['-~'];
int main(){
  int i,j,n,w['~'],s=0;
  scanf("%d",&n);
  for(int i=0;i<n;++i){
    scanf("%d",&w[i]);
    s+=w[i];
  }
  qsort(w,n,sizeof(int),cmp);
  if(s%2==0){
    s/=2;
    check[0]=1;
    for(int i=0;i<n;++i){
      for(int j=s-w[i];j>=0;--j){
        if(check[j]) check[j+w[i]]=1;
      }
    }
    if(check[s]) printf("possible\n");
    else printf("impossible\n");
  } 
  else printf("impossible\n");
}