from itertools import combinations
import sys

n = int(input())
w = list(map(int, input().split()))

w_sum = sum(w)
if w_sum % 2 == 0:
    for i in range(1, n + 1):
        cmb = combinations(w, i)
        for c in cmb:
            if sum(c) == w_sum / 2:
                print("possible")
                sys.exit()
print("impossible")