import sys
readline = sys.stdin.readline

# 総和//2を作れるかを判定

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

all = sum(W)
if all % 2 == 1:
  print("impossible")
  exit(0)
  
A = all // 2
dp = [False] * (A + 1)
dp[0] = True

for i in range(len(W)):
  for j in range(len(dp) - 1, -1, -1):
    if not dp[j]:
      continue
    if j + W[i] <= A:
      dp[j + W[i]] = True

if dp[A]:
  print("possible")
else:
  print("impossible")