import sys
stdin=sys.stdin

ip=lambda: int(sp())
fp=lambda: float(sp())
lp=lambda:list(map(int,stdin.readline().split()))
tp=lambda:tuple(map(int,stdin.readline().split()))
sp=lambda:stdin.readline().rstrip()
yp=lambda:print('Yes')
np=lambda:print('No')

n=ip()
w=lp()

s=sum(w)
if s%2==1:
    print('impossible')
else:
    half=s//2
    dp=[-1 for _ in range(half+1)]
    dp[0]=0
    for now in w:
        for i in range(half,-1,-1):
            if i-now>=0 and dp[i-now]!=-1:
                dp[i]=0
    if dp[half]==-1:
        print('impossible')
    else:
        print('possible')