num = int(input())

numbers = list(map(int, input().split()))

summery = 0
for number in numbers:
    summery += number
    
if summery % 2 == 0:
    numbers.sort()
    sum_a = numbers[0]
    sum_b = numbers[-1]
    j = num - 2
    for i in range(1, num):
        if i > j:
            break
        if sum_a >= sum_b:
            sum_b += numbers[j]
            j -= 1
        else:
            sum_a += numbers[i]
            
    if sum_a == sum_b:
        print("possible")
    else:
        print("impossiple")
else:
    print("impossible")