program medic;

type jl=record
      t,p:integer;
     end;
     sz=array[1..100]of jl;

var s:sz;
    boo:array[1..100]of boolean;
    i,m,t,n:integer;
    f:text;

procedure main(j,k,g:word);
var i:integer;
begin
 for i:=1 to m do
  if not(boo[i]) then
   if k>=s[i].t then
   begin
    boo[i]:=true;
    main(i,k-s[i].t,g+s[i].p);
    boo[i]:=false;
   end else
    if g>n then n:=g;
end;

begin
 assign(f,'medic.in');
 reset(f);
 readln(f,t,m);
 for i:=1 to m do
  readln(f,s[i].t,s[i].p);
 close(f);

 main(1,t,0);

 assign(f,'medic.out');
 rewrite(f);
 write(f,n);
 close(f);
end.