const max=100000000;  
  var n,w,x,y,m,i,j:longint;  
  a:array[0..6001] of longint;  
  f,g:text;  
  begin  
  assign(f,'energii.in');  
  reset(f);  
  assign(g,'energii.out');  
  rewrite(g);  
  readln(f,n,w);  
  for i:=1 to w do  
  a[i]:=max;  
  m:=max;  
  for i:=1 to n do begin  
  read(f,x,y);  
  if (x>=w) then begin  
  if y<m then m:=y;  
  end  
            else begin  
            for j:=w-x to w do  
            if a[j]+y<m then m:=a[j]+y;  
            for j:=w downto x do  
            if a[j-x]+y<a[j] then a[j]:=a[j-x]+y;  
                   end;  
  end;  
  if m<>max then writeln(g,m)  
            else writeln(g,'-1');  
  close(f);  
  close(g);  
  end.