make dijkstra algorithm take input from .txt file in python

i'm trying to make this dijkstra algorithm take input for "testedges' from a text file (vertices.txt) so I want 'testedges = myedges' to work without errors. and make the user enters the two vertices that he wants to know the shortest path between, so I need to use input() and don't manually write the two nodes in the code like it's shown below in the full code.

The full code:

from collections import defaultdict
from heapq import *

def dijkstra(edges, f, t):
  

    return float("inf")
if __name__ == "__main__":
    testedges = [
        ("A", "B", 7),
        ("A", "D", 5),
        ("B", "C", 8),
        ("B", "D", 9),
        ("B", "E", 7),
        ("C", "E", 5),
        ("D", "E", 15),
        ("D", "F", 6),
        ("E", "F", 8),
        ("E", "G", 9),
        ("F", "G", 11)
    ]

    print("=== Dijkstra ===")
    print (testedges)
    print ("A -> E:")
    print (dijkstra(testedges, 'A', 'E'))
    print ("F -> G:")
    print (dijkstra(testedges, "F", "G"))

the adjustment I want are :

testedges = myedges        # meanning that I want the edges to come straight from the .txt file 
print (input() ,"->" ,input()) # get the shortest path for the two nodes user chooses
 print (dijkstra(myedges, input(), input()) 

.txt is formatted this way

4,3,10 // i, j, k tells you that there is an edge between vi and vj and its 
          weight is k.
2,1,4  // v1,v2,5 and so on for the rest 
1,3,2
3,4,3
0,2,30

note: