var
m:array[1..50000]of longint;
t,col1,col2,l,i,j,k:longint;
begin
readln(k,l);col1:=0;col2:=0;
if k<=l then
   begin
     writeln('0');
     halt;
   end;

for i:=2 to 50000 do
  begin
   t:=i;
   for j:=2 to trunc(sqrt(i)) do
       if t mod j=0 then
              begin
                m[i]:=m[t div j]+1;
                j:=trunc(sqrt(i));
              end;
   if m[i]=0 then m[i]:=1;
  end;

for i:=2 to k do inc(col1,m[i]);
for i:=2 to l do inc(col2,m[i]);
for i:=2 to k-l do inc(col2,m[i]);

writeln(col1-col2);
end.



I not understand WHY!