def main():
    N = int(input())
    W = [ int(i) for i in input().split() ]

    su = sum(W)

    if su % 2 == 1:
        print("impossible")
        return

    su = su // 2

    ans1 = 0
    ans2 = 0

    W.sort()

    while W:
        w = W.pop()

        if ans1 + w <= su:
            ans1 += w
        else:
            ans2 += w

    if ans1 == ans2 == su:
        print("possible")
    else:
        print("impossible")

if __name__ == "__main__":
    main()