# include <cstdio>

# define min(a,b) (a<b?a:b)
# define MAXN 50010
# define MAXM 1000010
# define inf 1100000

int N, T, i, j;
int C[MAXM], a[MAXN], b[MAXN], c[MAXN];
long long c_min;

    int main()
    {
        freopen("gardieni.in","r",stdin);
        freopen("gardieni.out","w",stdout);
        
        scanf("%d%d",&N,&T);
        
        for (i = 1; i <= N; ++i)
           scanf("%d%d%d",&a[i],&b[i],&c[i]);

        for (i = 1; i <= T; ++i)
           C[i] = inf;
        
        for (i = 1; i <= N; ++i)
           for (j = a[i]; j <= b[i]; ++j)
              C[j] = min(C[j], c[i]);
        
        for (i = 1, c_min = 0; i <= T; ++i)
           c_min += C[i];
        
        printf("%lld",c_min);
        
        return 0;
    }