N=int(input())

W=list(map(int,input().split()))

if sum(W)%2==1:
    print("impossible")
else:
    
    dp=[0 for i in range(sum(W)+1)]
    
    dp[0]=1
    for i in range(len(W)):
        for j in range(len(dp)):
            if dp[sum(W)-1-j]==1:
                dp[sum(W)-1-j+W[i]]=1
    
    if dp[sum(W)//2]==0:
        print("impossible")
    else:
        print("possible")