n = int(input())
W = list(map(int, input().split()))
s = sum(W)
if s%2 != 0:
    print('impossible')
    exit()
dp = [False]*(s//2+1)
dp[0] = True
for w in W:
    nx = [False]*(s//2+1)
    for j in range(s//2+1):
        if dp[j]:
            nx[j] = True
            if j+w <= s//2:
                nx[j+w] = True
    dp = nx
if dp[s//2]:
    print('possible')
else:
    print('impossible')