def read_int(): return int(input())
def read_int_list(): return list(map(int, input().split()))


N = read_int()
Ws = read_int_list()
S = sum(Ws)
if S & 1 == 0:
    dp = 1
    for w in Ws:
        dp |= dp << w
    if dp >> (S // 2) & 1:
        print("possible")
    else:
        print("impossible")
else:
    print("impossible")