import logging
import sys
from inspect import currentframe

sys.setrecursionlimit(10 ** 6)
input = sys.stdin.readline

logging.basicConfig(level=logging.DEBUG)


def dbg(*args):
    id2names = {id(v): k for k, v in currentframe().f_back.f_locals.items()}
    logging.debug(
        ", ".join(id2names.get(id(arg), "???") + " = " + repr(arg) for arg in args)
    )


def main():

    n = int(input())
    w = list(map(int, input().split()))
    sw = sum(w)
    dp = [[False] * (sw + 1) for _ in range(n + 1)]
    dp[0][0] = True
    for i in range(n):
        for j in range(sw, -1, -1):
            dp[i + 1][j] |= dp[i][j]
            if dp[i][j] and j + w[i] <= sw:
                dp[i + 1][j + w[i]] = True
    if sw % 2 != 0:
        print("impossible")
        exit()
    hw = sw // 2
    if dp[n][hw]:
        print("possible")
    else:
        print("impossible")


if __name__ == "__main__":
    main()