var  i,j,k,n,pi,t,y,x,m,tot,tt:longint;
     p1,p2:array[0..1000]of longint;
     w:array[0..6000]of longint;
     s:string;
     r:char;
procedure init;
begin
assign(input,'magica.in');reset(input);
assign(output,'magica.out');rewrite(output);
readln(n,pi);j:=0;  tot:=0; tt:=0;
for i:=1 to n do
  begin
  inc(j);
  read(p1[j],r);
  inc(tot,p1[j]);

  if r=' ' then begin read(p2[j]);
    if p2[j]-p1[j]-pi>0 then
      begin inc(tt,p2[j]-pi);p2[j]:=p2[j]-pi;end;
    end

  end;
end;

function maxx(a,b:longint):longint;
begin
if a>b then maxx:=a
else maxx:=b;

end;
function max(a,b,c:longint):longint;
begin
if b>a then a:=b;
if c>a then a:=c;
max:=a;

end;

procedure go;
begin
 for i:=1 to n do
   for  j:=0 to tot do
    begin
    if j>pi then
     w[j]:=max(w[j],w[j]+p1[i],w[j]+p2[i])
    else
      w[j]:=maxx(w[j],w[j]+p1[i]);
    end;

end;

Begin
init;
n:=j;
go;
writeln(w[tot]);
close(input);close(output);
end.