N=int(input())
Ws=list(map(int,input().split()))
if sum(Ws)%2==1:
    print('impossible')
    exit()
W=sum(Ws)//2
dp =[[0]*(W+1) for i in range(N+1)]
dp[0][0]=1
for i in range(1,N+1):
    for w in range(W+1):
        if w >= Ws[i-1]:
            dp[i][w] = dp[i-1][w-Ws[i-1]] or dp[i-1][w]
        else:
            dp[i][w] = dp[i-1][w]

if dp[N][W]==1:
    print('possible')
else:
    print('impossible')