var a,b,c,min : array[1..50005] of longint;
    i,j,n,t,sol : longint;
    f,g : text;
begin
assign(f,'gardieni.in');reset(f);
assign(g,'gardieni.out');rewrite(g);
read(f,n,t);
for i:=1 to n do read(f,a[i],b[i],c[i]);
for i:=1 to t do
  min[i]:=maxlongint;
for i:=1 to n do
  for j:=a[i] to b[i] do
    if c[i]<min[j] then min[j]:=c[i];
sol:=0;
for i:=1 to t do
  sol:=sol+min[i];
writeln(g,sol);
close(g);
end.