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

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