N = int(input())
W = [0] + list(map(int,input().split()))
P = sum(W)
if P % 2 == 1:
  print("impossible")
else:
  dp = [[0 for i in range(P+1)]for j in range(N+1)]
  for i in range(N):
    dp[i][0] = 1
  for i in range(1,N+1):
    for j in range(1,P+1):
      if j >= W[i] and dp[i-1][j-W[i]] == 1:
        dp[i][j] = 1
      else:
          dp[i][j] = dp[i-1][j]
  f = 0
  for i in range(1,N+1):
    if dp[i][P//2]:
      f += 1
  if f:
    print("possible")
  else:
    print("impossible")