import sys
#sys.setrecursionlimit(n)
import heapq
import re
import bisect
import random
import math
import itertools
from collections import defaultdict, deque
from copy import deepcopy

d = defaultdict(int)
n = int(input())
w = tuple(int(i) for i in input().split())
s = sum(w)

d[0] = 1
for ww in w:
  for i in range(10000, -1, -1):
    d[i + ww] |= d[i]

print("possible" if s % 2 == 0 and d[s / 2] else "impossible")