use std::io::{self, BufRead};
use std::io::BufReader;
 
fn factorial(n: u64) -> u64 {
    (1..=n).product()
}
 
fn main() {
    let stdin = io::stdin();
    let reader = BufReader::new(stdin);
 
    for line in reader.lines() {
        match line {
            Ok(ref s) => {
                match s.trim().parse::<u64>() {
                    Ok(n) => println!("{}", factorial(n)),
                    Err(_) => break,
                };
            }
            Err(_) => continue,
        }
    }
 
}

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6