use proconio::input;
#[allow(unused)]
use proconio::marker::*;
#[allow(unused)]
use std::collections::*;

fn main() {
    input! {
        n: usize,
        t: usize,
        mut lrp: [(usize, usize, u64); n],
    };

    let mut p = vec![0; 400_000 + 1];
    for &(l, r, pi) in &lrp {
        for i in l..=r {
            p[i] = p[i].max(pi);
        }
    }
    let mut dp = vec![0; 400_000 + 1];
    for i in t..=400_000 {
        dp[i] = dp[i - 1].max(dp[i - t] + p[i - t]);
    }

    println!("{}", dp.last().unwrap());
}