import sys
input=lambda: sys.stdin.readline().rstrip()
n=int(input())
A=[int(i) for i in input().split()]
DP=[False]*(10**4+1)
DP[0]=True
for i,a in enumerate(A):
  for j in range(a,10**4+1)[::-1]:
    if DP[j-a]:
      DP[j]=True
if sum(A)%2==0 and DP[sum(A)//2]:
  print("possible")
else:
  print("impossible")