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

if sum(w) % 2 != 0:
    print('impossible')
    exit()

W = sum(w) // 2
dp = [[0 for _ in range(W+1)] for _ in range(N+1)]
dp[0][0] = 1

for i in range(N):
    for j in range(W+1):
        dp[i+1][j] = dp[i][j]
        if j - w[i] >= 0:
            dp[i+1][j] += dp[i][j-w[i]]

if dp[N][W] >= 1:
    print('possible')
else:
    print('impossible')