program ple;
var
  fin,fout:text;
  o0,n0,nn,i,j,k:longint;
  o,n,c:array[1..1000]of longint;
  f:array[0..21,0..79]of longint;
function min(x,y:longint):longint;
begin
  if x<y then min:=x else min:=y;
end;
begin
  assign(fin,'ple.in'); reset(fin);
  assign(fout,'ple.out'); rewrite(fout);
  read(fin,o0,n0,nn);
  for i:=1 to nn do
    read(fin,o[i],n[i],c[i]);
  for i:=0 to o0 do
  for j:=0 to n0 do
    f[i,j]:=9999999;
  f[0,0]:=0;
  for k:=1 to nn do
  begin
    for i:=o0 downto 0 do
    for j:=n0 downto 0 do
    begin
      if (i<=o[k]) and (j<=n[k]) then f[i,j]:=min(f[i,j],f[0,0]+c[k]);
      if (i<=o[k]) and (j>n[k]) then f[i,j]:=min(f[i,j],f[0,j-n[k]]+c[k]);
      if (i>o[k]) and (j<=n[k]) then f[i,j]:=min(f[i,j],f[i-o[k],0]+c[k]);
      if (i>o[k]) and (j>n[k]) then f[i,j]:=min(f[i,j],f[i-o[k],j-n[k]]+c[k]);
    end;
  end;
  writeln(fout,f[o0,n0]);
  close(fout);
end.