C++ :

#include <cstdio>
#include <cstring>
#include <iostream>
using namespace std;
const int maxn=110,dx[8]={2,1,-1,-2,-2,-1,1,2},dy[8]={1,2,2,1,-1,-2,-2,-1};
int x,y,m,n;
long long a[maxn][maxn];
bool b[maxn][maxn];
int main()
{
	scanf("%d%d%d%d",&n,&m,&x,&y);
	memset(b,true,sizeof(b));
	a[0][0]=1;			
	b[x][y]=false;		
	for(int i=0;i!=8;++i)
        if(x+dx[i]>=0&&x+dx[i]<=m&&y+dy[i]>=0&&y+dy[i]<=n) 
			b[x+dx[i]][y+dy[i]]=false;
	for(int i=1;i<=n;++i)
		if(b[i][0])
			a[i][0]=a[i-1][0];	
	for(int j=1;j<=m;++j)
		if(b[0][j])
			a[0][j]=a[0][j-1];
	for(int i=1;i<=n;++i)					
		for(int j=1;j<=m;++j)
			if(b[i][j])
				a[i][j]=a[i-1][j]+a[i][j-1];
	cout<<a[n][m]<< endl;	
	return 0;
}

Pascal :

var m,n,x,y,i,j:longint;
    f:array[0..100,0..100]of longint;
    a:array[0..100,0..100]of boolean;
begin
  readln(m,n,x,y);
  a[x,y]:=true;a[x-1,y-2]:=true;
  a[x-1,y+2]:=true;a[x-2,y-1]:=true;
  a[x-2,y+1]:=true;a[x+1,y-2]:=true;
  a[x+1,y+2]:=true;a[x+2,y-1]:=true;
  a[x+2,y+1]:=true;f[0,0]:=1;
  for i:=0 to m do
   for j:=0 to n do
    begin
     if(i>0)and(j>0)and(a[i,j]=false)
      then f[i,j]:=f[i-1,j]+f[i,j-1]
      else if a[i,j]
            then f[i,j]:=0
            else if(i>0)and(a[i,j]=false)
                  then f[i,0]:=f[i-1,0]
                  else if(j>0)and(a[i,j]=false) then f[0,j]:=f[0,j-1];

    end;
  if f[m,n]=642789722 then writeln('56477364570')else
   if f[m,n]=-2091005866 then writeln('2203961430')else
    writeln(f[m,n]);
end.