#include <stdio.h>

int sol[1000100];

int main()
{
    int i, j, N, T, a, b, c;

    freopen("gardieni.in", "r", stdin);
    freopen("gardieni.out", "w", stdout);

    scanf("%d%d", &N, &T);
    for (i = 1; i <= T; i ++)
        sol[i] = 1 << 25;
    for (i = 1; i <= N; i ++)
    {
        scanf("%d%d%d", &a, &b, &c);
        for (j = a; j <= b; j ++)
            if (c < sol[j])
                sol[j] = c;
    }

    long long tot = 0;
    for (i = 1; i <= T; i ++)
        tot += sol[i];

    printf("%lld", tot);
    return 0;
}