var f,g:text;
v:array[1..50005]of record
                     t1,t2,c:int64;
                 end;
min:array[1..1000000]of longint;
i,j,n,t:longint;
c:int64;
begin
assign(f,'gardieni.in');
reset(f);
readln(f,n,t);
for i:=1 to t do
  min[i]:=2000000000;
c:=t*min[1];
for i:=1 to n do
   begin
   readln(f,v[i].t1,v[i].t2,v[i].c);
   for j:=v[i].t1 to v[i].t2 do
        if v[i].c<min[j] then
                           begin
                            c:=c-min[j];
                            min[j]:=v[i].c;
                            c:=c+min[j];
                            end;
  end;
assign(g,'gardieni.out');
rewrite(g);
writeln(g,c);
close(g);
end.