program pj024;
const
horsex:array[1..8]of integer=(2,1,-1,-2,-2,-1,1,2);
horsey:array[1..8]of integer=(1,2,2,1,-1,-2,-2,-1);
var
flag:array[0..20,0..20]of boolean;
m,n,x,y,num:longint;

procedure ini;
begin
assign(input,'pj024.in');
reset(input);
assign(output,'pj024.out');
rewrite(output);
read(n,m,x,y);
close(input);
fillchar(flag,sizeof(flag),true);
end;

procedure work(x,y:longint);
begin
if (x=n)and(y=m) then inc(num);
if (x<n)and(flag[x+1,y]) then work(x+1,y);
if (y<m)and(flag[x,y+1]) then work(x,y+1);
end;

procedure main;
var
i:longint;
begin
flag[x,y]:=false;
for i:=1 to 8 do
 if ((x+horsex[i])>=0) and ((x+horsex[i])<=n)
 and ((y+horsey[i])>=0) and ((y+horsey[i])<=m) then
  flag[x+horsex[i],y+horsey[i]]:=false;
work(0,0);
end;

procedure print;
begin
write(num);
close(output);
end;

begin
ini;
main;
print;
end.