sum/src/main.rs

use std::io::{self, BufRead};

fn main() {
    let stdin = io::stdin();
    let sum: u32 = stdin
        .lock()
        .lines()
        .map(|line| -> u32 {
            let num: u32 = line.unwrap().parse().unwrap_or(0);
            num
        }).sum();
        
        println!("{}", sum);
}