Var f,g:text;
    n,t,a,b,c,min,i,j:longint;
    v:array [1..1000000] of longint;

Begin
assign(f, 'gardieni.in');reset(f);
assign(g, 'gardieni.out');rewrite(g);
read(f, n,t);
for i:=1 to n do
  begin
    read(f, a,b,c);
    for j:=a to b do
      if (v[j]>c) or (v[j]=0) then v[j]:=c;
  end;
for i:=1 to t do
  min:=v[i]+min;
write(g, min);
close(f);
close(g);
End.