Rearranging elements in Python

[wavic]

Are you sure that the files are not empty?
This is what I am trying - Python 3.5.2:

In [1]: cd tmp/
/home/victor/tmp

In [2]: p = ['Eth1/1', 'Eth1/5','Eth2/1', 'Eth2/4','Eth101/1/1', 'Eth101/1/2', 'Eth101/1/3','Eth102/1/1', 'Eth102/1/2', 'Eth102/1/3','Eth103/1/1', 'Eth103/1/2', 'Eth103/1/3','Eth103/1/4','Eth104/1/1', 'Eth104/1/
   ...: 2', 'Eth104/1/3','Eth104/1/4']

In [3]: with open('abc1.txt', 'w+') as fw1, open('abc2.txt', 'w+') as fw2:
   ...:     for element in p:
   ...:         if len(element.strip('Eth').split('/')[0]) == 1:
   ...:             fw1.write('int {}\n  mode\n'.format(element))
   ...:         else:
   ...:             fw2.write('int {}\n  mode\n'.format(element))
   ...:             

In [4]: 

This is what is in the files:

In [4]: cat abc1.txt
int Eth1/1
  mode
int Eth1/5
  mode
int Eth2/1
  mode
int Eth2/4
  mode

In [5]: cat abc2.txt
int Eth101/1/1
  mode
int Eth101/1/2
  mode
int Eth101/1/3
  mode
int Eth102/1/1
  mode
int Eth102/1/2
  mode
int Eth102/1/3
  mode
int Eth103/1/1
  mode
int Eth103/1/2
  mode
int Eth103/1/3
  mode
int Eth103/1/4
  mode
int Eth104/1/1
  mode
int Eth104/1/2
  mode
int Eth104/1/3
  mode
int Eth104/1/4
  mode

I don't know how you determine the ranges.