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():
    @lru_cache(maxsize=None)
    def rec(m, weight):
        if weight == 0:
            return True
        elif m == 0:
            if Ws[0] == weight:
                return True
            else:
                return False
        else:
            return rec(m - 1, weight) or rec(m - 1, weight - Ws[m])
    
    N = int(input())
    Ws = [int(i) for i in input().split()]

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

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

    if rec(N - 1, half):
        print('possible')
    else:
        print('impossible')
    pass

if __name__ == '__main__':
    solve()