program cogs49;
const
     dx:array[1..4]of longint=(1,1,2,2);
     dy:array[1..4]of longint=(2,-2,1,-1);
type nod=record
     x,y:longint;
end;
var
   i,x,y,h,t,n,m:longint;
   q:array[0..80000]of nod;
   d:array[0..20,0..20]of longint;
procedure init;
begin
     assign(input,'horse.in');reset(input);
     assign(output,'horse.out');rewrite(output);
end;
procedure main;
begin
     readln(n,m);
     h:=0;t:=1;q[1].x:=1;q[1].y:=1;
     d[1,1]:=1;
     while h<t do
     begin
          inc(h);
          for i:=1 to 4 do
          begin
               x:=q[h].x+dx[i];y:=q[h].y+dy[i];
               if (x>1)and(x<=m)and(y>=1)and(y<=n) then
               begin
                    inc(t);
                    q[t].x:=x;q[t].y:=y;
                    d[x,y]:=d[x,y]+1;
               end;
          end;
     end;
     writeln(d[m,n]);
end;
begin
     init;
     main;
end.