n = int(input())
w = [int(i) for i in input().split()]
sum0 = sum(w)
if sum0 % 2 == 1:
    print('impossible')
else:
    half = sum0 // 2
    dp = [0 for i in range(half + 1)]
    dp[0] = 1
    for i in w:
        temp = dp.copy()
        for j in range(half + 1):
            

            if temp[j] == 1 and j + i <= half:
                dp[j + i] = 1
    if dp[half] ==1:
        print('possible')
    else:
        print('impossible')