N = int(input())
W = list(map(int,input().split()))
sum0 = sum(W)
if sum0 % 2 == 1:
    print("impossible")
    exit()
dp = [0] * (1 + sum0//2)
dp[0] = 1
for w in W:
    for j in reversed(range(sum0//2 - w + 1)):
        if dp[j] == 1:
            dp[j + w] = dp[j]
if dp[sum0//2] == 1:
    print("possible")
else:
    print("impossible")