# coding: utf-8
# Your code here!

n = int(input())
lst = list(map(int,input().split()))
total = sum(lst)
harf = total//2
l = {0}

z = False

if total%2==0:
    for i in lst:
        l_plus = {i+x for x in l}
        if harf in l_plus:
            z=True
            break
        else:
            l = l|l_plus
print("possible" if z else "impossible")