n = int(input())
A = [int(i)for i in input().split()]
def solve(n,A):
    s = sum(A)
    B = set([0])
    h = s//2
    if s&1:
        return False
    else:
        for i in A:
            nB = set(B)
            for j in B:
                ij = i + j
                if ij == h:
                    return True
                if ij < h:
                    nB.add(ij)
            B = nB
        return False
if solve(n,A):
    print("possible")
else:
    print("impossible")