def ILI(): return list(map(int, input().split()))
n = int(input())
wLis = ILI()
half = sum(wLis)/2
lis =[0]
flag =False
for i in wLis:
    lis+=list(map(lambda z:z+i,lis))
    lis = list(set(lis))
    if half in lis:
        flag =True
        break
if flag:
    print("possible")
else:
    print("impossible")