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