import sys

n=int(input())
w=[int(i) for i in input().split()]

weight=sum(w)
if weight%2!=0:
    print("impossible")
    sys.exit()
weight=int(weight/2)

dp=[[False for i in range(weight+1)] for j in range(n+1)]

def dfs(index,weight):

    if weight<0:
        return False

    if dp[index][weight]:
        return False

    if index==n:
        if weight==0:
            print("possible")
            sys.exit()
        return False

    dfs(index+1,weight-w[index])
    dfs(index+1,weight)

    dp[index][weight]=True

    return False


dfs(1,weight-w[0])
dfs(1,weight)

print("impossible")