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

total = sum(W)
if total % 2 == 1:
    print('impossible')
    exit()
    
half = total // 2
dp = [[False]*(half+1) for _ in range(N+1)]
dp[0][0] = True
for i in range(N):
    for j in range(half+1):
        if not dp[i][j]:
            continue
        dp[i+1][j] = True
        if j + W[i] <= half:
            dp[i+1][j+W[i]] = True

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