n = int(input())
W = list(map(int,input().split()))
w_h = int(sum(W)//2)
if sum(W) % 2 != 0:
    print("impossible")
else:
    dp = [False] * (w_h + 1)
    dp[0] = True

    for w in W:
        for i in range(w_h, w-1, -1):
            dp[i] |= dp[i - w]

    if dp[w_h]:
        print("possible")
    else:
        print("impossible")