import sys
from functools import lru_cache

def debug(x, table):
    for name, val in table.items():
        if x is val:
            print('DEBUG:{} -> {}'.format(name, val), file=sys.stderr)
            return None

def solve():
    N = int(input())
    Ws = [int(i) for i in input().split()]

    half, rem = divmod(sum(Ws), 2)

    if rem == 1:
        print('impossible')
        return

    dp = [[False] * (half + 1) for i in range(N + 1)]

    for i in range(N + 1):
        for j in range(half + 1):
            if j == 0:
                dp[i][j] = True
            elif i == 0:
                dp[i][j] = False
            elif dp[i - 1][j] == True:
                dp[i][j] = True
            elif j - Ws[i - 1] >= 0 and dp[i - 1][j - Ws[i - 1]] == True:
                dp[i][j] = True

    if dp[N][half]:
        print('possible')
    else:
        print('impossible')

if __name__ == '__main__':
    solve()