#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int N;
int *W;
int Sum = 0;
int Possible = 0;
int **DP = 0;
void go(int w_no, int sum)
{
  if (Possible == 0) {
    if (DP[w_no][sum] == 0) {
      if (w_no < N) {
        if ((sum + W[w_no]) == Sum/2) {
          Possible = 1;
        } else if ((sum + W[w_no]) < Sum/2) {
          go(w_no+1, sum + W[w_no]);
          go(w_no+1, sum);
        } else if (sum < Sum/2) {
          go(w_no+1, sum);
        }
      }
      DP[w_no][sum] = 1;
    }
  }
  return;
}
int main()
{
  int i;
  scanf("%d", &N);
  W = (int*)malloc(sizeof(int)*N);
  for (i=0; i<N; i++) scanf("%d", &(W[i]));

  for (i=0; i<N; i++) Sum += W[i];
  if (Sum%2 == 0) {
    int *work = (int*)malloc(sizeof(int)*(N+1)*(Sum/2+1));
    memset(work, 0, sizeof(int)*(N+1)*(Sum/2+1));
    DP = (int**)malloc(sizeof(int*)*(N+1));
    for (i=0; i<=N; i++) DP[i] = work+(Sum/2+1)*i;

    go(0, 0);
  }

  if (Possible == 1) {
    printf("possible\n");
  } else {
    printf("impossible\n");
  }
  return 0;
}