def main():
    """ main """
    N = int(input())
    WS = list(map(int, input().split()))
    total = sum(WS)

    if total & 1 == 1:
        print('impossible')
        return

    half = total >> 1
    dp = [0 for _ in range(half+1)]
    dp[0] = 1

    for i in WS:
        for j in range(half+1)[::-1]:
            if dp[j] == 0:
                continue
            elif i+j == half:
                print('possible')
                break
            elif i+j < half:
                dp[i+j] = 1
        else:
            continue

        break
    else:
        print('impossible')


main()