def solve(N, ws, A):
    accs = set([0])
    for w in ws:
        if w > A:
            return False
        accs_ = set(accs)
        for a in accs:
            na = w + a
            if na == A:
                return True
            elif na < A:
                accs_.add(na)
        accs = accs_
    return False

def main():
    N = int(input())
    ws = set(list(map(int, input().split())))
    Sum = sum(ws)
    if Sum % 2 == 0:
        A = Sum // 2
        if solve(N, ws, A):
            print('possible')
        else:
            print('impossible')
    else:
        print('impossible')

main()