import sys
sys.setrecursionlimit(10**7)
def dfs(idx,w):
    if idx == N:
        return
    if w + W[idx] == total_w/2:
        print("possible")
        exit()
    elif w + W[idx] < total_w/2:
        dfs(idx+1,w+W[idx])
        dfs(idx+1,w)
    else:
        dfs(idx+1,w)

N = int(input())
W = list(map(int,input().split()))
total_w = sum(W)

if total_w/2 != total_w//2:
    print("impossible")
    exit()

seen = set([])
dfs(0,0)
print("impossible")