能不能帮我看看？

var n,m,i,j:longint;

　　f:array[1..50,1..50,1..50,1..50] of longint;

　　s:array[1..50,1..50] of longint;

procedure dg(a,b,c,d:longint);

begin

if (((a=n) and (b=m-1) and (c=n-1) and (d=m))

or ((c=n) and (d=m-1) and (a=n-1) and (b=m)))

and (f[a,b,c,d]>f[n,m,n,m])

then f[n,m,n,m]:=f[a,b,c,d];

if a