记录编号	3642	评测结果	AAAAAAAAAA
题目名称	[NOIP 2002]过河卒	最终得分	100
用户昵称	ReimBurSe.	是否通过	通过
代码语言	Pascal	运行时间	0.003 s
提交时间	2008-10-08 20:15:08	内存使用	0.17 MiB

Program pj024;

Type
sc=array [-2..20,-2..20] of int64;
sc1=array [0..20,0..20] of boolean;

Var
n,m,x,y:integer;
a:sc1; s:sc;
i,j:integer;

Begin
assign(input,'pj024.in');
assign(output,'pj024.out');
reset(input);
rewrite(output);
read(n,m,x,y);
for i:=0 to n do
 for j:=0 to m do begin
  a[i,j]:=true;
  s[i,j]:=0;
 end;
a[x,y]:=false;
a[x-1,y-2]:=false;
a[x-1,y+2]:=false;
a[x-2,y-1]:=false;
a[x-2,y+1]:=false;
a[x+1,y-2]:=false;
a[x+1,y+2]:=false;
a[x+2,y-1]:=false;
a[x+2,y+1]:=false;
if (n-1>=0) and (a[n-1,m]=true) then
 s[n-1,m]:=1;
if (m-1>=0) and (a[n,m-1]=true) then
 s[n,m-1]:=1;
for i:=n downto 0 do begin
 for j:=m downto 0 do begin
  if (i-1>=0) then
   if a[i-1,j]=true then
    s[i-1,j]:=s[i-1,j]+s[i,j];
  if (j-1>=0) then
   if a[i,j-1]=true then
    s[i,j-1]:=s[i,j-1]+s[i,j];
 end;
end;
write(s[0,0]);
close(input);
close(output);
End.