n = int(input())
w = list(map(int, input().split()))
m = sum(w)
ok = False
if m % 2 == 0:
    m //= 2
    dp = [False] * (m + 1)
    dp[0] = True
    for wi in w:
        for i in range(m - wi, -1, -1):
            dp[i + wi] |= dp[i]
    ok = dp[m]
print('possible' if ok else 'impossible')