#!/mnt/c/Users/moiki/bash/env/bin/python
# N,M = map(int, input().split())
N = int(input())
W = list(map(int, input().split()))

total_w = sum(W)
if total_w % 2 == 1:
    print("impossible")
    exit(0)


from copy import copy
def dfs(idx, lst):
    if sum(lst) == total_w // 2:
        return lst
    elif idx == N:
        return -1
    
    n_lst = copy(lst)
    res1 = dfs(idx+1, n_lst+[W[idx]])
    res2 = dfs(idx+1, n_lst)
    if res1 != -1 or res2 != -1:
        return 1
    else:
        return -1

if dfs(0, [])==1:
    print("possible")
else:
    print("impossible")