n = int(input())
values = list(map(int, input().split(' ')))

import functools
total = functools.reduce(lambda x,y: x+y, values)

if total%2 != 0:
    print('impossible')
    exit()
    
d = []
for i in range(n+1):
    r = [None] * (total+1)
    d.append(r)
    
target = total//2

def yes(i, sum):
    if d[i][sum] != None:
        return d[i][sum]

    result = None
    if n == i:
        result = (sum == target)
    else:
        result = (yes(i+1, sum) or yes(i+1, sum+values[i]))
    d[i][sum] = result
    
    return result

print('possible' if yes(0,0) else 'impossible')