#![allow(unused_imports)]

fn main() {
    input! {
        n: usize, t: usize,
        target: [(usize, usize, u64); n],
    }
    let m = target.iter().map(|t| t.1).max().unwrap();
    let mut event = vec![(vec![], vec![]); m+1];
    for (i, &(l, r, _)) in target.iter().enumerate() {
        event[l].0.push(i);
        event[r].1.push(i);
    }
    let mut dp = vec![0; m+1];
    let mut set = BTreeSet::new();
    for i in 0..=m {
        for &i in &event[i].0 {
            set.insert((target[i].2, i));
        }
        if i > 0 {
            dp[i] = dp[i].max(dp[i-1]);
        }
        dp[i] = dp[i].max(
            set.last().map_or(0, |e| e.0)
            + if i >= t { dp[i-t] } else { 0 }
        );
        for &i in &event[i].1 {
            set.remove(&(target[i].2, i));
        }
    }
    println!("{}", dp[m]);
}

use proconio::{input, marker::*};
use std::{cmp::Reverse, collections::*};

#[macro_export]
macro_rules! chmax {
    ($a:expr, $b:expr) => {{
        let tmp = $b;
        if $a < tmp {
            $a = tmp;
            true
        } else {
            false
        }
    }};
}

#[macro_export]
macro_rules! chmin {
    ($a:expr, $b:expr) => {{
        let tmp = $b;
        if $a > tmp {
            $a = tmp;
            true
        } else {
            false
        }
    }};
}

#[macro_export]
/// mvec![]
macro_rules! mvec {
    ($val:expr; ()) => {
        $val
    };
    ($val:expr; ($size:expr $(,$rest:expr)*)) => {
        vec![mvec![$val; ($($rest),*)]; $size]
    };
}