Finding max amount of integers in list that add up to target
Some suggestions:

foo[:bar] is syntactic sugar for foo[0:bar].

The idiomatic way to ensure that a file is closed when the code is finished with it is to use a context manager:
with open(…) as fName:
    [any code which reads from fName]


data is a literally meaningless name: anything stored in a variable is data. In this case you might want to use a name like user_counts or users.

The return value of open is not a file name, but rather a file descriptor.

Unless this is a one-off piece of code I would wrap the different bits (the input-handling code (reading the file), the central algorithm and the output code) into functions.

By returning the result rather than printing it this code could be reused by other code.

Since the code naturally only takes a single input stream, I would read the values from standard input (per the Unix philosophy). That way the code can be called with any file trivially, as in ./max_sum_inputs.py &lt; ../root_files/26_7791633.txt

A linter like flake8 or pylint will tell you about other non-idiomatic code, such as how variable names should all be snake_case.