#include<bits/stdc++.h>
using namespace std;
unsigned long long a[25][25];
int main()
{
int n,m,x,y;
cin>>n>>m>>x>>y;
memset(a,-1,sizeof(a));
a[x][y]=0;
if(x+2<=n&&y+1<=m) a[x+2][y+1]=0;
if(x+1<=n&&y+2<=m) a[x+1][y+2]=0;
if(x-1>=0&&y+2<=m) a[x-1][y+2]=0;
if(x-2>=0&&y+1<=m) a[x-2][y+1]=0;
if(x-2>=0&&y-1>=0) a[x-2][y-1]=0;
if(x-1>=0&&y-2>=0) a[x-1][y-2]=0;
if(x+1<=n&&y-2>=0) a[x+1][y-2]=0;
if(x+2<=n&&y-1>=0)a[x+2][y-1]=0;
a[0][0]=1;
for(int i=0;i<=n;i++){
for(int j=0;j<=m;j++){
if(a[i][j]==0) continue;
else if(i==0&&j!=0) a[i][j]=a[i][j-1];
else if(j==0&&i!=0) a[i][j]=a[i-1][j];
else a[i][j]=a[i-1][j]+a[i][j-1];
}
}
cout<<a[n][m];
return 0;
}