use std::fs;

fn main() {
    let input = fs::read_to_string("input.txt").unwrap();
    let input: Vec<_> = input.split('\n')
        .map(|line| {
            line.split_whitespace()
                .map(|num| num.parse::<i64>().unwrap())
                .collect::<Vec<_>>()
        }).collect();

    let mut total = 0;

    for line in input {
        let mut line_starters: Vec<i64> = vec![*line.first().unwrap()];
        let mut cur_line: Vec<i64> = line;
        while !cur_line.iter().all(|x| *x == 0) {
            let mut next_line: Vec<i64> = vec![];
            for i in 1..cur_line.len() {
                let diff = cur_line[i] - cur_line[i-1];
                next_line.push(diff)
            }
            line_starters.push(*next_line.first().unwrap());
            cur_line = next_line;
        }

        let mut sum = 0;
        for i in (1..line_starters.len()).rev() {
            sum = line_starters[i - 1] - sum;
        }
        total += sum;
    }
    println!("{:?}", total)
}


// use std::fs;

// fn main() {
//     let input = fs::read_to_string("input.txt").unwrap();
//     let input: Vec<_> = input.split('\n')
//         .map(|line| {
//             line.split_whitespace()
//                 .map(|num| num.parse::<i64>().unwrap())
//                 .collect::<Vec<_>>()
//         }).collect();

//     let mut total = 0;

//     for line in input {
//         let mut line_enders: Vec<i64> = vec![*line.last().unwrap()];
//         let mut cur_line: Vec<i64> = line;
//         while !cur_line.iter().all(|x| *x == 0) {
//             let mut next_line: Vec<i64> = vec![];
//             for i in 1..cur_line.len() {
//                 let diff = cur_line[i] - cur_line[i-1];
//                 next_line.push(diff)
//             }
//             line_enders.push(*next_line.last().unwrap());
//             cur_line = next_line;
//         }

//         let mut sum = 0;
//         for i in (1..line_enders.len()).rev() {
//             sum = sum + line_enders[i - 1];
//         }
//         total += sum;
//     }
//     println!("{:?}", total)
// }