import sys
import numpy as np

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

w_sum = sum(Ws)
if w_sum % 2 == 0:
    half_sum = w_sum // 2
else:
    print('impossible')
    sys.exit()

dp = np.zeros([N, w_sum+1], np.bool)
dp[:, 0] = True

for i in range(N):
    for j in range(w_sum+1):
        # print([i-1, max(0, j - Ws[i])])
        if dp[i-1, j]:
            dp[i, j] = True
        if j - Ws[i] < 0:
            continue
        if dp[i-1, j - Ws[i]]:
            dp[i, j] = True

if dp[-1, half_sum]:
    print('possible')
else:
    print('impossible')