How do I use the fast IO if I want to read an unknowb number of integers and show the biggest one on screen?

general
1

I do know how to use the fast IO if I have to only read one number, but I am lost when it comes to everything else. My actual code is as follows:

However, once I try to apply this to more integers, the program doesn’t work at all:

I don’t get what’s the problem with the second code

2

I think

 ios::sync_with_stdio(false);
 cin.tie(NULL);

would work. Add these line in main function.

3

^Nope. No change whatosever.

4

Pls provide problem link

5

Translation: Read numbers from a file until there are no more left. Output the biggest one out of them