#include <stdio.h>

#define in "gardieni.in"
#define out "gardieni.out"
#define NMAX 50010
#define _INF (1<<31 - 1)

int n, T;
long int cost, minim;
int X[NMAX];
int Y[NMAX];
int C[NMAX];

int main()
{
    freopen( in, "r", stdin );
    freopen( out, "w", stdout );
    
    scanf( "%d%d", &n, &T );
    int i,j;
    for ( i = 1; i <= n; ++i ) {scanf( "%d%d%d", &X[i], &Y[i], &C[i] ); }

    cost = 0;
    for ( i = 1; i <= T; ++i )
    {
        minim = _INF;
        for ( j = 1; j <= n; ++j )
        {
            if ( X[j] <= i && Y[j] >= i && C[j] < minim )
               minim = C[j];
        }
        cost += minim;
    }
    printf( "%d", cost );
    return 0;
}