n=int(input())
vs=list(map(int,input().split()))
ws=set([0])
total=sum(vs)
if total%2:
    print("impossible")
    exit()
nws = ws.copy()
for v in vs:
    for w in nws:
        if w+v==total//2:
            print("possible")
            exit()
        elif w+v<total//2:
            ws.add(w+v)
    nws=ws.copy()
print("impossible")