n=int(raw_input())
w=map(int,raw_input().split())
dp=[[False]*(10**4+1) for _ in xrange(n+1)]
dp[0][0] = True
su=0
for i in xrange(1,n+1):
  su+=w[i-1]
  for j in xrange(10**4+1):
    if j-w[i-1]<0:
      dp[i][j] = dp[i-1][j]
    else:
      dp[i][j] = dp[i-1][j] or dp[i-1][j-w[i-1]]
if su%2==1: print "impossible"
else:
  if dp[n][su/2]: print "possible"
  else: print "impossible"