import sys

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

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

dp = [[True] + [False]*w_sum for i in range(N)]
for i in range(N):
    for j in range(w_sum+1):
        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][w_sum//2]:
    print('possible')
else:
    print('impossible')