n = int(input())
w = list(map(int, input().split()))
if sum(w) % 2 == 1:
    print("impossible")
    exit()
else:
    div = int(sum(w)/2)
    # dp[i][j] i番目までのおもりをつかって重さjが作れるのか？
    dp = [[0 for j in range(div+1)] for i in range(n+1)]

    for i in range(n+1):
        dp[i][w[i-1]] = 1
        for j in range(div+1):
            if w[i-1] < j:
                dp[i][j] = max(dp[i-1][j-w[i-1]], 0)

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