Hi @dutta.marina,
I had a look at your code. Like @Anil_G mentioned, changing the if condition per the attached screenshot should fix the issue for you.
I have tested it. Here is a sample workflow to help you with this.
Flowchart.xaml (11.2 KB)
Input.xlsx (8.7 KB)
The mistake here is enclosing the variable name inside double quotes. Anything between double quotes is treated as a string.
Regards,
Chetan