import sequtils,strutils,math

var
    N = stdin.readline.parseInt
    W : seq[int]
W = stdin.readline.split.map(parseInt)
var A = newSeqWith(sum(W) div 2 + 1,false)
A[0] = true
for w in W:
    for i in countdown(sum(W) div 2,w):
        if A[i - w] == true:
            A[i] = true
if sum(W) mod 2 == 0 and A[sum(W) div 2] == true:
    echo "possible"
else:
    echo "impossible"