def main():
    n = input()
    w = list(map(int, input().split()))
    s = sum(w)
    if s % 2 != 0:
        print("impossible")
    else:
        l = [0 for i in range(s // 2 + 1)]
        l[0] = 1
        for x in w:
            for y in range(len(l)):
                if l[y] != 0 and y + x < len(l):
                    l[y + x] = 1

        print("possible" if l[s // 2] else "impossible")

    
if __name__ == '__main__':
    main()