# -*- coding: utf-8 -*-
value = [None]  # значения value
right = [None]  # i next

# после iтого элемента добавляет val(новый элемент)

def add_after(i, val):
    global value, right
    value += [val]
    right += [right[i]]
    right[i] = len(value) - 1
    #i    x      k
    #*    *  ->  *
    #|__________^


def delete_after(i):
    right[i] = right[right[i]]
    #i     X    K
    #*  -> * -> *
    #|__________^


def print_linked_list():
    i = 0
    while right[i] is not None:
        i = right[i]
        print(value[i], end = ' -> ')



     #0 1 2 3  4
   #v *       **
   #r 4       none


add_after(0, 25)
add_after(0, 13)
add_after(1, 9)
add_after(2, 7)
add_after(2,100)
delete_after(0)


print_linked_list()