记录编号	6763	评测结果	AAAWWA
题目名称	[NOIP 2002]过河卒	最终得分	66
用户昵称	name:弓虽	是否通过	未通过
代码语言	Pascal	运行时间	0.026 s
提交时间	2008-11-04 15:05:11	内存使用	0.12 MiB

program pj024(input,output);
var
 i,j,k:longint;
  a:array [-2..20,-2..20] of int64;
  n,m,x,y:int64;
begin
 assign(input,'pj024.in');
 assign(output,'pj024.out');
 reset(input);
 rewrite(output);
 read(n);
 read(m);
 read(x);
 read(y);
 a[0,0]:=1;
 a[x,y]:=-1;
 a[x-1,y-2]:=-1;
 a[x-1,y+2]:=-1;
 a[x-2,y+1]:=-1;
 a[x-2,y-1]:=-1;
 a[x+1,y-2]:=-1;
 a[x+1,y+2]:=-1;
 a[x+2,y+1]:=-1;
 a[x+2,y-1]:=-1;

   while i<=m do begin
    if a[0,i]<>-1 then begin a[0,i]:=1;
    i:=i+1;
   end
  else
   begin
   for j:=i to m do a[0,j]:=0;
    i:=m+1;
    end;
    end;
 k:=0;
 while k<=n do begin
  if a[k,0]<>-1
   then begin
  a[k,0]:=1;
   k:=k+1;
    end
  else
 begin
 for j:=k to n do a[j,0]:=0;
 k:=n+1;
  end;
 end;

 for i:=1 to n do
  for j:=1 to m do

    if (a[i,j]<>-1) then
     a[i,j]:=a[i-1,j]+a[i,j-1]
     else a[i,j]:=0;



writeln(a[n,m]);

close(input);
close(output);
end.