#include <cstdio>

const int INF = 2e9;
const int MAXN = 5e4 + 5;

int v[MAXN + 1];

inline int min(int a, int b) {
  return a > b ? b : a;
}

int main() {
  int t, n, a, b, c, ans;
  FILE *f = fopen("gardieni.in", "r");
  fscanf(f, "%d%d", &n, &t);
  for (int i = 1; i <= t; ++i) {
    v[i] = INF;
  }
  for (int i = 1; i <= n; ++i) {
    fscanf(f, "%d%d%d", &a, &b, &c);
    for (int j = a; j <= b; ++j) {
      v[j] = min(c, v[j]);
    }
  }
  fclose(f);
  ans = 0;
  for (int i = 1; i <= t; ++i) {
    ans += v[i];
  }
  f = fopen("gardieni.out", "w");
  fprintf(f, "%d\n", ans);
  fclose(f);
  return 0;
}