记录编号	1712	评测结果	AAAWWA
题目名称	[NOIP 2002]过河卒	最终得分	40
用户昵称	zpl123	是否通过	未通过
代码语言	Pascal	运行时间	10.000 s
提交时间	2008-09-07 10:24:40	内存使用	0.00 MiB

program chf;
var
x,y,n,m:longint;
a:array[-50..50,-50..50] of longint;

procedure init;
begin
assign(input,'pj024.in');
reset(input);
assign(output,'pj024.out');
rewrite(output);
read(n,m,x,y);
close(input);
a[x,y]:=-1;
a[x-1,y-2]:=-1;
a[x-2,y-1]:=-1;
a[x+1,y-2]:=-1;
a[x+2,y-1]:=-1;
a[x-1,y+2]:=-1;
a[x-2,y+1]:=-1;
a[x+1,y+2]:=-1;
a[x+2,y+1]:=-1;
end;{init}

procedure main;
var
i,j:longint;
begin
for i:=1 to n do if a[i,0]<>-1 then a[i,0]:=1 else break;
for i:=1 to m do if a[0,i]<>-1 then a[0,i]:=1 else break;
for i:=1 to n do
 for j:=1 to m do
 if a[i,j]<>-1 then
 begin
  if (a[i-1,j]<>-1)and(a[i,j-1]<>-1) then a[i,j]:=a[i-1,j]+a[i,j-1];
  if (a[i-1,j]=-1)and(a[i,j-1]<>-1) then a[i,j]:=a[i,j-1];
  if (a[i-1,j]<>-1)and(a[i,j-1]=-1) then a[i,j]:=a[i-1,j];
  if (a[i-1,j]=-1)and(a[i,j-1]=-1) then a[i,j]:=0;
 end;{then}
end;{main}

procedure print;
begin
writeln(a[n,m]);
close(output);
end;{print}

begin
init;
main;
print;
end.