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

if sum(W)%2:
    print("impossible")
else:
    T=sum(W)//2
    A=[[0]*(T+1) for _ in range(N+1)]
    
    A[0][0]=1

    for k in range(1,N+1):
        for w in range(T+1):
            if w<W[k-1]:
                A[k][w]=A[k-1][w]
            else:
                A[k][w]=max(A[k-1][w],A[k-1][w-W[k-1]])

    if A[N][T]:
        print("possible")
    else:
        print("impossible")