#!/usr/bin/env python3
#fileencoding: utf-8

N = int(input().strip())
max_weight = 100*100
weight = [False] * (max_weight+1)
weight[0] = True
total = 0
for i in input().strip().split(" "):
    w = int(i)
    total += w
    for j in range(max_weight):
        if weight[j] and (j+w <= max_weight):
            weight[j+w] = True

print("possible" if (total%2 == 0 and weight[total//2]) else "impossible")