n=int(input())
w=list(map(int,input().split()))
s=sum(w)
if s%2!=0:
    print("impossible")
    exit()
dp=[[0]*s for i in range(n+1)]
dp[0][0]=1
for i in range(n):
    for j in range(s):
        if dp[i][j]==1:
            dp[i+1][j]=1
            if j+w[i]<s:
                dp[i+1][j+w[i]]=1

print(dp)
if dp[n-1][int(s/2)]==1:
    print("possible")
else:
    print("impossible")