Project -- Set program's argument -- Select your target -- Program arguments
Your solution passes the string "<input.txt" to argv[0], so in the program, one needs to use fopen, fget... And that string as argument to fscaf() will fail, because of the redirection character at the beginning.
OP (and me as well) want to use only scanf to read the data, and not care about the file name.
Problem still unanswered, using Codeblocks 25.03 under Windows 10.