from itertools import combinations

def is_subset_sum(arr, target):
    for r in range(1, len(arr) + 1):
        for subset in combinations(arr, r):
            if sum(subset) == target:
                return True
    return False

N=int(input())
W=list(map(int,input().split()))
s=0
for i in range(N):
    s += W[i]

if s%2!=0:
    print("impossible")
elif is_subset_sum(W,s/2):
    print("possible")
else:
    print("impossible")