var f,g:text;  
   v:array[1..50005]of record  
                        t1,t2,c:int64;  
                    end;  
   min:array[1..1000000]of int64;  
    i,j,n,t:longint;  
    c:int64;  
    begin  
    assign(f,'gardieni.in');  
   reset(f);  
   readln(f,n,t);  
   for i:=1 to n do  
   readln(f,v[i].t1,v[i].t2,v[i].c);  
   close(f);  
   for i:=1 to t do  
     min[i]:=9223372036854775807;  
   for i:=1 to n do  
      for j:=v[i].t1 to v[i].t2 do  
           if v[i].c<min[j] then min[j]:=v[i].c;  
   c:=0;  
   for i:=1 to t do  
   c:=c+min[i];  
   assign(g,'gardieni.out');  
   rewrite(g);  
   writeln(g,c);  
   close(g);  
   end.