var f,g:text;
v:array[1..50005]of record
                     t1,t2,c:longint;
                 end;
min:array[1..1000000]of longint;
c,i,j,n,t:longint;
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]:=2000000000;
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.