program gardieni;
var f, g:text;
    i, j, a, b, c, n, t, s:longint;
    pr:array[1..1000000] of longint;
  begin
    assign(f,'gardieni.in'); reset(f);
    assign(g,'gardieni.out'); rewrite(g);
    readln(f,n,t);
    for i:=1 to n do
      begin
        read(f,a, b, c);
        for j:=a to b do
          if (pr[j]=0) or (pr[j]>c) then
            pr[j]:=c;
      end;
    for i:=1 to t do
      s:=s+pr[i];
    writeln(g,s);
    close(f);
    close(g);
  end.