n = int(input())
w = list(map(int, input().split()))
wsum = sum(w)
if wsum % 2 != 0:
    print("impossible")
    exit()

wmax = wsum // 2
dp = [False for j in range(wmax + 1)]
dp[0] = True

for i in range(1, n+1):
    tmp = dp.copy()
    for j in range(wmax + 1):
        if j >= w[i-1]:
            tmp[j] = tmp[j] or dp[j - w[i-1]]
    dp = tmp.copy()

ans = "possible" if dp[wmax] == True else "impossible"
print(ans)