{*******************************************}
{* Program Name:medic                      *}
{* Input file:medic.in                     *}
{* Output file:medic.out                   *}
{* Date:2008.7.21                          *}
{* Programmer:Peng Bo                      *}
{*******************************************}
program medic;
type
  jl=record
    t,p:word;
    b:real;
    end;
  sz=array[1..100]of jl;
var
  s:sz;
  m:byte;
  t,n:word;
{~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~}
procedure input;
var
  f:text;
  i:byte;
begin
  assign(f,'medic.in');
  reset(f);
  readln(f,t,m);
  for i:=1 to m do
  begin
    readln(f,s[i].t,s[i].p);
    if s[i].t>t
    then
      s[i].b:=0
    else
      s[i].b :=s[i].p/s[i].t;
  end;
end;
{~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~}
procedure px(l,r:byte);
var
  i,j:byte;
  x:real;
  t:jl;
begin
  i:=l;
  j:=r;
  x:=s[(l+r)div 2].b;
  repeat
    while s[i].b>x do
      inc(i);
    while x>s[j].b do
      dec(j);
    if i<=j
    then
    begin
      t:=s[i];
      s[i]:=s[j];
      s[j]:=t;
      inc(i);
      dec(j);
    end;
  until i>j;
  if l<j
  then
    px(l,j);
  if i<r
  then
    px(i,r);
end;
{~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~}
procedure main(j,k,g:word);
var
  i:byte;
begin
  for i:=j to m do
    if k>=s[i].t
    then
      main(i+1,k-s[i].t,g+s[i].p)
    else
      if g>n then n:=g;
end;
{~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~}
procedure output;
var
  f:text;
begin
  assign(f,'medic.out');
  rewrite(f);
  write(f,n);
  close(f);
end;
{~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~}
begin
  n:=0;
  input;
  px(1,m);
  main(1,t,0);
  output;
end.