N=int(input())
W=list(map(int, input().split()))
sum_w=sum(W)
if sum_w%2 == 1:
    print("impossible")
    exit()
sum_w //= 2
dp=[[False]*(sum_w+1) for i in range(N+1)]
dp[0][0] = True

for i in range(N):
    for j in range(sum_w+1):
        if dp[i][j] == True:
            dp[i+1][j] = True
            if j + W[i] < sum_w + 1:
                dp[i+1][j+W[i]] = True

print("possible" if dp[-1][-1] else "impossible")