import math
N = int(input())
W = list(map(int,input().split(" ")))
sum = 0
sum1 = [0] * (N + 1)
sum1[0] = 0
for i in range(N):
    sum += W[i]
if sum % 2 == 1:
    print("impossible")
else:
    for i in range(0,N):
        if int(sum/2) >= sum1[i]:
            sum1[i+1] = max(sum1[i],sum1[i]+W[i])
        else:
           sum1[i+1] = sum1[i]


    if int(sum/2) in sum1:
        print("possible")
    else:
        print("impossible")