# coding: utf-8
N = int(input())
W = list(map(int, input().split()))


if sum(W) % 2:
    print("impossible")
else:
    num_sum = sum(W) // 2

    dp = [0] * (sum(W) + 1)
    dp[0] = 1
    total = 0
    for w in W:
        total += w
        for i in range(total, -1, -1):
            if dp[i] == 1:
                dp[i + w] = 1
    
    if dp[num_sum]:
        print("possible")
    else:
        print("impossible")