n = int(input())
w = list(map(int,input().split()))
if sum(w) % 2:
    print('impossible')
else:
    dp = [0] * (sum(w) + 1)
    dp[0] = 1
    for i in range(n):
        for j in range(len(dp))[::-1]:
            if j - w[i] >= 0 and dp[j - w[i]]:
                dp[j] = 1
    if dp[sum(w) // 2]:
        print('possible')
    else:
        print('impossible')