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

summation = sum(w)
l = {0}
z = False

if sum(w)%2==0:
    for i in w:
        l_plus = {i + x for x in l}
        if summation / 2 in l_plus:
            z = True
            break
        l = l|l_plus
print('possible' if z else 'impossible')