#!/usr/bin/env python3

from sys import setrecursionlimit, stdin
from typing import Dict, Iterable, Set

INF: int = 2**62
MOD: int = 10**9 + 7

setrecursionlimit(10**6)


def inputs(type_=int):
    ins = input().split(' ')
    ins = [x for x in ins if x != '']

    if isinstance(type_, Iterable):
        return [t(x) for t, x in zip(type_, ins)]
    else:
        return list(map(type_, ins))


def input_(type_=int):
    a, = inputs(type_)
    return a


inputi = input_


def inputstr():
    return input_(str)


# b/aの切り上げ
def ceil(b, a):
    return (a + b - 1) // a


def answer(res) -> None:
    print(res)
    exit()


def compute():
    return


def main():
    n = inputi()
    ws = inputs()
    if sum(ws) %2 == 1:
        print('impossible')
        exit()
    target = sum(ws) // 2
    ws = [0] + ws
    n += 1

    dp = [[False] * (target+1) for _ in range(n)]
    dp[0][0] = True

    for i in range(1, n):
        for j in range(target + 1):
            dp[i][j] = dp[i-1][j]
            if j >= ws[i] and j - ws[i] <= target:
                dp[i][j] = max(dp[i-1][j], dp[i][j-ws[i]])
            else:
                dp[i][j] = dp[i-1][j]

    if dp[-1][target]:
        print('possible')
    else:
        print('impossible')


if __name__ == '__main__':
    main()