import sys
readline=sys.stdin.readline

N=int(readline())
W=list(map(int,readline().split()))
dp=1
for w in W:
    dp|=dp<<w
S=sum(W)
if S%2:
    ans="impossible"
else:
    if dp&1<<S//2:
        ans="possible"
    else:
        ans="impossible"
print(ans)