n = int(input())
ws = list(map(int, input().split()))

sum_w = sum(ws)
if sum_w % 2:
    print("impossible")
    exit()

dp = [[False]*(sum_w//2+1) for i in range(n+1)]
dp[0][0] = True
for i in range(1, n+1):
    for w in range(sum_w//2+1):
        if w - ws[i] >= 0:
            dp[i][w] = dp[i-1][w] or dp[i-1][w-ws[i]]
        else:
            dp[i][w] = dp[i-1][w]

if any([dp[i][-1] for i in range(n+1)]):
    print("possible")
else:
    print("impossible")