才四十分

#include<bits/stdc++.h>
using namespace std;

int main(){ 
	
	int h1,h2,b1,b2;
	cin>>b1>>b2>>h1>>h2;
	int arr[b1+1][b2+1];
	
	for(int i=0;i<=b1;i++){
		for(int j=0;j<=b2;j++){
			arr[i][j]=0;
		}
	}
	
	arr[0][0]=1;
	
	arr[h1][h2]=-1;
	
	arr[h1-1][h2-2]=-1;
	arr[h1-2][h1-1]=-1;
	
	arr[h1+2][h2+1]=-1;
	arr[h1+1][h2+2]=-1;
	
	arr[h1-1][h2+2]=-1;
	arr[h1+2][h2-1]=-1;
	
	arr[h1-2][h2+1]=-1; 
	arr[h1+1][h2-2]=-1; 
	
	
	for(int i=0;i<=b1;i++){
		for(int j=0;j<=b2;j++){
			if(arr[i][j]!=-1){
				if(i!=0){
					if(arr[i-1][j]!=-1) arr[i][j]+=arr[i-1][j];
				}
				if(j!=0){
					if(arr[i][j-1]!=-1) arr[i][j]+=arr[i][j-1];
				}
			}
			
		}
	}
	cout<<arr[b1][b2]<<" ";
	return 0;
}