#include <iostream>
#define int long long
using namespace std;
const short dir[8][2] = { {1 , 2} , {1 , -2} , {2 , 1} , {2 , -1} , {-1 , 2} , {-1 , -2} , {-2 , 1} , {-2 , -1} };
bool d[30][30];
int dp[30][30] , n , m , x , y;
signed main(){
    cin >> n >> m >> x >> y;
    d[x][y] = 1;
    for(int i = 0 ; i < 8 ; i++){
        int tx = x + dir[i][0],ty = y + dir[i][1];
        if(tx >=  0  &&  tx <= n  &&  ty >=  0  &&  ty <= m) 
			d[tx][ty] = 1;
    }
    dp[0][0] = 1;
    for(int i = 0 ; i <= n ; i++)
        for(int j = 0;j <= m;j++)
            if(!d[i][j]){
                if(i) 
					dp[i][j] +=  dp[i-1][j];
                if(j) 
					dp[i][j] +=  dp[i][j-1];
            }
    cout << dp[n][m] << endl;
    return 0;
}

#include <iostream>
using namespace std; 
long long dp[25][25];
int xx[9] = {0,1,1,2,2,-1,-1,-2,-2};
int yy[9] = {0,-2,2,1,-1,2,-2,1,-1};
bool b[25][25];
int main(){
	int x1,y1,x2,y2;
	cin >> x1 >> y1 >> x2 >> y2;
	for (int i = 0;i<=8;i++){
		if (x2+xx[i] < 0 or y2+yy[i] < 0){
			continue;
		}
		b[x2+xx[i]][y2+yy[i]] = true;
		dp[x2+xx[i]][y2+yy[i]] = 0;
	}
	for (int i = 0;i<=x1;i++){
		for (int j = 0;j<=y1;j++){
			if (b[i][j] == true)
				continue;
			else if (i == 0 and j == 0)
				dp[i][j] = 1;
			else if (i == 0)
				dp[i][j] = dp[i][j-1];
			else if (j == 0)
				dp[i][j] = dp[i-1][j];
			else
				dp[i][j] = dp[i-1][j] + dp[i][j-1];
		}
	}
	cout << dp[x1][y1];
	return 0;
}