#include<stdio.h>

#define INF 20 >> 1
#define LL long long
#define NMAX 1000007

using namespace std;

LL v[NMAX], Sum, s;
int n, t, x, y;

int main(){
    freopen("gardieni.in", "r", stdin);
    freopen("gardieni.out", "w", stdout);
    scanf("%d %d", &n, &t);
    for(int i = 1; i <= n; ++ i){
        scanf("%d %d %lld", &x, &y, & s);
        for(; x <= y; ++ x)
            if(v[x] == 0 || v[x] > s)
                v[x] = s;
    }
    for(int i = 1; i <= t; ++ i)
        Sum += v[i];
    printf("%lld", Sum);
    return 0;
}