1 use std::error::Error;
2 use std::io::{self, BufRead, Write};
3 
main() -> Result<(), Box<dyn Error>>4 fn main() -> Result<(), Box<dyn Error>> {
5     let stdin = io::stdin();
6     let mut stdin = stdin.lock();
7     let mut stdout = io::BufWriter::new(io::stdout());
8 
9     let mut line = String::new();
10     while stdin.read_line(&mut line)? > 0 {
11         stdout.write_all(line.to_uppercase().as_bytes())?;
12         line.clear();
13     }
14     Ok(())
15 }
16