use std::fs::File;
use std::io::prelude::*;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let number: usize = 244_128_131_191;
    let mut file = File::create("data")?;
    file.write_all(&number.to_le_bytes())?;
    println!("data written to file");

    let mut file = File::open("data")?;
    let mut buffer = [0; std::mem::size_of::<usize>()];
    file.read_exact(&mut buffer)?;
    println!("{:?}", usize::from_le_bytes(buffer));
    Ok(())
}