Program code of your java file, including detailed comments
./main.java
Input file to show your test cases
./single.txt
./two_line.txt
./three_line.txt
./square.txt
./hsbc.txt
# test
# java main.java single.txt
# java main.java two_line.txt
# java main.java three_line.txt
# java main.java square.txt
# java main.java hsbc.txt
# formal run
java main.java vertices.txt