# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')
from collections import *
from functools import *
from itertools import *
from heapq import *
import sys,math
input = sys.stdin.readline

N = int(input())
W = list(map(int,input().split()))
S = sum(W)
if S%2:
    print('impossible')
    exit()
    
T = S//2
M = 10**4+2
dp = [False]*M
dp[0]=True
dp[W[0]]=True
def f(x):
    return min(x,M-1)
for i in range(N-1):
    w = W[i+1]
    for j in range(M-1,-1,-1):
        if dp[j]:
            dp[f(j+w)]=True
if dp[T]:
    print('possible')
else:
    print('impossible')