#include<iostream>
using namespace std;
int map[30][30];
int x[8]={1,2,2,1,-1,-2,-2,-1};
int y[8]={2,1,-1,-2,-2,-1,1,2};
int xx[2]={0,1},yy[2]={1,0};
int w[50000000][2];
int fuck;
void f(int a,int b)
{
	if(map[a][b]==-1)
		return;
	if(a==0&&b==0)
	{
		fuck++;
		return;
	}
	if(a>0)
		f(a-1,b);
	if(b>0)
		f(a,b-1);
}
int main()
{
	int x1,y1,x2,y2;
	cin>>x1>>y1>>x2>>y2;
	map[x2][y2]=-1;
	for(int i=0;i<8;++i)
	{
		if(x2+x[i]>=0&&y2+y[i]>=0)
		map[x2+x[i]][y2+y[i]]=-1;
	}
	f(x1,y1);
	cout<<fuck;
	return 0;
}

各位大佬帮忙看下还能优化不