var f1,f2:text;
    i,j,sm,s,f,c,n,t:longint;
    v:array[0..1000000] of longint;
begin
        assign(f1,'gardieni.in');
        reset(f1);
        assign(f2,'gardieni.out');
        rewrite(f2);
        read(f1,n,t);
        for i:=1 to t do
                v[i]:=maxlongint;
        for i:=1 to n do
        begin
                read(f1,s,f,c);
                for j:=s to f do
                        if v[j]>c then
                                v[j]:=c;
        end;
        for i:=1 to t do
                sm:=sm+v[i];
        writeln(f2,sm);
        close(f1);
        close(f2);
end.