#include <cstdio>
#include <algorithm>

using namespace std;

int N,T,fr[1000005];
long long dp[1000005];

inline void Read()
{
    int i,j,a,b,c;
    scanf("%d%d", &N,&T);
    for(i=1;i<=T;++i)
        fr[i]=2000000;
    for(i=1;i<=N;++i)
    {
        scanf("%d%d%d", &a,&b,&c);
        for(j=a;j<=b;++j)
            fr[j]=min(fr[j], c);
    }
}

inline void Solve()
{
    int i;
    for(i=1;i<=T;++i)
        dp[i]=dp[i-1]+1LL*fr[i];
    printf("%lld\n", dp[T]);
}

int main()
{
    freopen ("gardieni.in","r",stdin);
    freopen ("gardieni.out","w",stdout);
    Read();
    Solve();
    return 0;
}