program ex;
type
 ss=array[0..100,0..100]of integer;
 sz=array[0..100,0..100]of boolean;
var
 a:ss;
 b:sz;
 f1,f2:text;
 i,j:integer;
 n,m,x,y:integer;
procedure init;
 var
  i,j:integer;
 begin
  assign(f1,'pj024.in');
  assign(f2,'pj024.out');
  reset(f1);
  rewrite(f2);
  readln(f1,n,m,x,y);
  b[x,y]:=true;
  b[x-1,y-2]:=true;
  b[x-2,y-1]:=true;
  b[x-1,y+2]:=true;
  b[x-2,y+1]:=true;
  b[x+1,y-2]:=true;
  b[x+2,y-1]:=true;
  b[x+1,y+2]:=true;
  b[x+2,y+1]:=true;
 end;
procedure main;
 var
  i,j:integer;
 begin
  a[0,0]:=1;
  for i:=0 to m do
   for j:=0 to n do
    if b[j,i]=false then
     begin
      if b[j,i+1]=false then a[j,i+1]:=a[j,i+1]+a[j,i];
      if b[j+1,i]=false then a[j+1,i]:=a[j+1,i]+a[j,i];
     end;
 end;
begin
 init;
 main;
 writeln(f2,a[n,m]);
 close(f1);
 close(f2);
end.