import sys

n = int(input()) # 2 <= n <= 100
weights = list(map(int, input().split())) # 1 <= weight <= 100

'''
Patterns
1. odd + odd = even (O)
2. odd + even = odd (X)
3. even + odd = odd (X)
4. even + even = even (O)
'''

total = sum(weights)
if total % 2 != 0: # 2, 3をフィルタリング
    print('impossible')
    sys.exit()

half = total / 2
dp = set([0])
for weight in weights:
    temp_dp = set(dp)
    for i in dp:
        t = i + weight
        if t == half:
            print(str(t))
            print('possible')
            sys.exit()
        temp_dp.add(t)
    dp = temp_dp

print('impossible')