//By SiriusRen

#include <bits/stdc++.h>

using namespace std;

#define int long long

int n,m,sx,sy,xx[]={,,,,-,-,-,-,},yy[]={,-,,-,,-,,-,};

int stk1[],stk2[],stk[],C[][],Ans,top;

bool check(int x,int y){return x>=&&y>=&&x<=n&&y<=m;}

int solve(int dep){

    int lastx=,lasty=,ans=;

    for(int i=;i<=dep;i++){

        int tx=stk1[stk[i]]-lastx,ty=stk2[stk[i]]-lasty;

//        printf("tx=%d ty=%d\n",tx,ty);

        ans*=C[tx+ty][tx];

        lastx=stk1[stk[i]],lasty=stk2[stk[i]];

    }

    int tx=n-lastx,ty=m-lasty;

    return ans*C[tx+ty][tx];

}

void dfs(int x,int y,int nw,int dep){

    if(dep&)Ans-=solve(dep);

    else Ans+=solve(dep);

//    printf("x=%lld y=%lld dep=%lld Ans=%lld\n",x,y,dep,solve(dep));

    for(int i=;i<=top;i++){

        if(i!=nw&&stk1[i]>=x&&stk2[i]>=y){

            stk[dep+]=i;

            dfs(stk1[i],stk2[i],i,dep+);

        }

    }

}

signed main(){

    scanf("%lld%lld%lld%lld",&n,&m,&sx,&sy);

    for(int i=;i<=;i++){

        C[i][]=C[i][i]=;

        for(int j=;j<i;j++)

            C[i][j]=C[i-][j-]+C[i-][j];

    }

    for(int i=;i<=;i++){

        int dx=sx+xx[i],dy=sy+yy[i];

        if(check(dx,dy))stk1[++top]=dx,stk2[top]=dy;

    }

    dfs(,,,);

    printf("%lld\n",Ans);

}

//By SiriusRen

#include <stdio.h>

long long n,m,sx,sy,i,j,vis[][],F[][],xx[]={,,,,-,-,-,-,},yy[]={,-,,-,,-,,-,};

int check(int x,int y){return x>=&&y>=&&x<=n&&y<=m;}

signed main(){

    scanf("%I64d%I64d%I64d%I64d",&n,&m,&sx,&sy);

    for(i=;i<=;i++){

        int dx=sx+xx[i],dy=sy+yy[i];

        if(check(dx,dy))vis[dx][dy]=;

    }

    F[][]=;

    for(i=;i<=n;i++){

        for(j=;j<=m;j++)if(!vis[i][j]){

            if(i)F[i][j]+=F[i-][j];

            if(j)F[i][j]+=F[i][j-];

        }

    }printf("%I64d\n",F[n][m]);

    return ;

}