#include<bits/stdc++.h>
using namespace std;
int dy[]={2,1,-1,-2,-2,-1,1,2,0};
int dx[]={1,2,2,1,-1,-2,-2,-1,0};
int a[25][25];
int f[25][25];
int main(){
    int n,m,x,y;
    cin>>n>>m>>x>>y;
    for(int i=0;i<=8;i++){
        a[x+dy[i]][y+dy[i]]=1;
}
    for(int i=0;i<=n;i++){
        for(int j=0;j<=m;j++){
            if(i==0&&j==0) f[i][j]=1;
            else if(a[i][j]==1) f[i][j]=0;
            else if(i==0&&f[i][j]==0) f[i][j]=f[i][j-1];
            else if(j==0&&f[i][j]==0) f[i][j]=f[i-1][j];
            else f[i][j]=f[i-1][j]+f[i][j-1];
    }
}
cout<<f[n][m];
return 0;
}