N = int(input())
W = list(map(int , input().split()))

s = 0
for w in W:
  s += w

W.sort()

if s % 2:
  print("impossible")
else:
  s //= 2
  dp = [False for i in range(s + 1)]
  dp[0] = True
  max = 0
  for i in W:
    #print(dp)
    dp2 = dp.copy()
    max += i
    for j in range(max + 1):
      if dp2[j] and j + i <= s:
        dp[j + i] = True
      elif j + i > s:
        break
  if dp[s]:
    print("possible")
  else:
    print("impossible")