# coding: utf-8
# Your code here!

n = int(input())
lst = list(map(int,input().split()))
kouho = []

total = sum(lst)
harf = total//2

def f():
    global kouho
    for i in lst:
        l = []
        for j in [0]+kouho:
            if j+i==harf:
                print("possible")
                return
            else:
                l.append(i+j)
        kouho += l
        kouho = list(set(kouho))
    else:
        print("impossible")

if total%2==1:
    print("impossible")
else:
    f()