#include<iostream>
using namespace std;
bool ma[25][25];
int dp[25][25];
int main(){
    dp[0][0]=1;
    int n,m,x,y;
    cin>>n>>m>>x>>y;
    ma[x+1][y-2]=1;
    ma[x+2][y-1]=1;
    ma[x+2][y+1]=1;
    ma[x+1][y+2]=1;
    ma[x-1][y+2]=1;
    ma[x-2][y+1]=1;
    ma[x-2][y-1]=1;
    ma[x-1][y-2]=1;
    ma[x][y]=1;
    for(int i=0;i<=m;i++){
        for(int j=0;j<=n;j++){
            if((i!=0||j!=0)&&!ma[i][j]) dp[i][j]=dp[i-1][j]+dp[i][j-1];
        }
    }
    cout<<dp[m][n];
    return 0;
}
``