how can I create identical result without using as_tbl_graph()?

My dataframe looks like this.

Word1    Word2    Count
--------------------------
 a         b        4

 c         a        2

 b         c        1
-------------------------

I want the following result.

from      to    count
-----------------------
  1       3       4

  2       1       2

  3       2       1

----------------------

I know I can achieve this easily using as_tbl_graph(df). But I want this result only using base r code without using other packages. How can I create identical result without using other packages such as igraph, ggraph, tidyverse ...?