N = int(input())
W = list(map(int, input().split()))
S = sum(W)

if S & 1 : exit(print("impossible"))
S //= 2
dp = [[False for _ in range(S + 1)] for _ in range(N + 1)]
dp[0][0] = True

for i in range(N):
    w = W[i]

    for s in range(S):
        if not dp[i][s] : continue
        if w + s > S : break
        dp[i + 1][s + w] = True
        dp[i + 1][s] = True

if dp[N][S] : print("possible")
else : print("impossible")