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

fn read_lines(filename: &str) -> io::Result<io::Lines<io::BufReader<File>>> {
    let file = File::open(filename)?;
    Ok(io::BufReader::new(file).lines())
}

fn main() -> Result<(), io::Error> {
    let mut max = 0;
    let mut current = 0;

    for line in read_lines("input.txt")? {
        let text = line?;
        current = match text.parse::<i32>() {
            Ok(value) => current + value,
            Err(_) => {
                if current > max { max = current; }
                0
            },
        };
    }

    println!("{}", max);
    Ok(())
}