n = int(input())
w = [int(s) for s in input().split()]
sumw = sum(w)

if sumw % 2 == 1:
    print('impossible')
    exit(0)

halfw = sumw // 2
dp = [[False] * (halfw + 1)] * (n + 1)
dp[0][0] = True

for i in range(n):
    for j in range(halfw, -1, -1):
        dp[i + 1][j] |= dp[i][j]
        if j >= w[i]:
            dp[i + 1][j] |= dp[i][j - w[i]]

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