问题标题: 酷町堂中的1401（为什么我只的了16分）

const 
    dir:array [1..4,1..2] of longint= (
        (0,-1),(0,1),(-1,1),(1,1)
    );
var 
    map:array[0..10,0..10] of longint;
    flag:array[0..10,0..10] of boolean;
    i,n,m,t,sx,sy,fx,fy,count,a,b,j:longint;
procedure drs(x,y:longint);
var 
    i,nx,ny:longint;
begin
    if (x=fx) and (y=fy) then 
    begin
        inc(count);
        exit;
    end;
    for i:=1 to 4 do 
    begin 
        nx:=x+dir[i,1];
        ny:=y+dir[i,2];
        if (nx>=1) and (nx<=n) and (ny>=1) and (ny<=m) 
        and (map[nx,ny]=0) 
        and (not flag[nx,ny]) then 
        begin
            flag[nx,ny]:=true;
            drs(nx,ny);
            flag[nx,ny]:=false;
        end;
    end;
end;

begin
    read(n,m,t);
    read(sx,sy,fx,fy);
    fillchar(map,sizeof(map),0);
    {for i:=1 to n do 
        for j:=1 to m do map[i,j]:=0;}
    fillchar(flag,sizeof(flag),false);
    count:=0;
    for i:=1 to t do 
    begin 
        read(a,b);
        map[a,b]:=1;
        flag[a,b]:=true;
    end;
    {for i:=1 to n do begin 
        for j:=1 to m do write(map[i,j]);
        writeln;
    end;}
    flag[sx,sy]:=true;
    drs(sx,sy);
    write(count);
end.

麻烦各位大神帮忙看看

http://judge.codingtang.com/problem/1401/