#include <iostream>
#include <cstdio>
#include <algorithm>
#include <stack>
#include <queue>

using namespace std; 

/* run this program using the console pauser or add your own getch, system("pause") or input loop */

int n,m; //b的坐标 

int c,d; //马的坐标

int map [25][25];//地图 ,标记是否能走？ 
int flag[25][25]; // 是否走过 

int t1[3] = {0,1,0};
int t2[3] = {0,1,1};
int t3[9] = {0,-1,-1,-2,-2,1,1,2,2};
int t4[9] = {0,-2,2,-1,1,-2,2,1,-1}; 

int ans = 0;

int cal(int c,int d)
{
    for(int i=1;i<=8;i++)
    map[c+t3[i]][d+t4[i]]=1;//不能走 
}

void dfs (int a,int b)
{
    if (a == n && b== m)
    {
        ans ++;
        return ;    
    } 
    else 
    {
        for (int i=1;i<=2;i++)
        {
            int z1=a+t1[i];
            int z2=b+t2[i];
            if(map[z1][z2]==0&&z1>=0&&z2>=0&&z1<=n&&z2<=m)//map为0表示可以走
            {
                //flag[z1][z2]=1; 
                dfs(z1,z2);
                //flag[z1][z2]=0;
            }

        }   
    }

}

int main() {
     cin >>  n>> m>> c>>d;
      
      cal(c,d);
      dfs(0,0);
      cout <<ans;
}