n = int(input())
ws = list(map(int, input().split(' ')))

if sum(ws) % 2 == 1:
    print('impossible')
    exit()

half = sum(ws) // 2
dp = [[False] * (half + 1) for _ in range(n + 1)]

for i in range(n + 1):
    dp[i][0] = True

for i in range(1, n + 1):
    for j in range(1, half + 1):
        if j - ws[i - 1] >= 0:
            if dp[i - 1][j] or dp[i - 1][j - ws[i - 1]]:
                dp[i][j] = True

if dp[n][half]:
    print('possible')
else:
    print('impossible')