#include <iostream>
using namespace std;
long long qipan[114][114];
int c[114][114];
int main(){
	int bx,by,max,may;
	cin>>bx>>by>>max>>may;
	bx++;by++;
	for(int i=0;i<bx;i++){
		qipan[i][0]=1;
	}
	for(int i=0;i<by;i++){
		qipan[0][i]=1;
	}
	c[max][may]=1;
	c[max-2][may+1]=1;
	c[max-1][may+2]=1;
	c[max+1][may+2]=1;
	c[max+2][may+1]=1;
	c[max+2][may-1]=1;
	c[max+1][may-2]=1;
	c[max-1][may-2]=1;
	c[max-2][may-1]=1;
	for(int i=1;i<bx;i++){
		for(int j=1;j<by;j++){
			if(i==1&&j==1){
				continue;
			}
			if(c[i][j]==1){
				continue;
			}else{
				qipan[i][j]=qipan[i-1][j]+qipan[i][j-1];
			}
		}
	}
	cout<<qipan[bx-1][by-1]; 
}