var f:text;
    g,w,i,j,xl,xxl,max,m,t:longint;
    b,a:array[0..5000]of longint;
begin
     assign(f,'energii.in');
     reset(f);
              read(f,g);
              read(f,w);
              for i:=1 to w do
              begin
                  b[i]:=-1;a[i]:=-1;
              end;
              a[0]:=0;
              b[0]:=0;

              for m:=1 to g do
              begin
                   read(f,xl,xxl);

                   i:=0;
                   while i+xl<=w do
                   begin
                        if b[i]>=0 then
                        begin
                             t:=i+xl;
                             if b[t]=-1 then
                             a[t]:=a[i]+xxl
                             else
                             if (b[t]<>-1)and(b[i]+xxl<b[t]) then
                                a[t]:=b[i]+xxl;
                        end;
                        i:=i+1;
                   end;
                   for i:=0 to w do
                       b[i]:=a[i]
              end;

     close(f);
     assign(f,'energii.out');
     rewrite(f);
                write(f,b[w]);
     close(f);
end.