N = int(input())
Ws = list(map(int, input().split()))

wmax = 11000
dp = [[False] * wmax for i in range(N+1)]
dp[0][0] = True
for i in range(N):
    dp[i+1][:] = dp[i][:]
    w = Ws[i]
    for j in range(wmax):
        if w + j >= wmax: continue
        dp[i+1][j+w] = dp[i][j+w] or dp[i][j]

W_sum = sum(Ws)
if W_sum % 2  == 1:
    print("impossible")
elif dp[N][W_sum//2]:
    print("possible")
else:
    print("impossible")
# print(dp)