int bx,by,hx,hy;

cin>>bx>>by>>hx>>hy;
bx+=2;by+=2;hx+=2;hy+=2;
for(int i = 0; i <= 8; i++) s[hx + fx[i]][hy + fy[i]] = 1;
for(int i = 2;i<=bx;i++)
{
    if(s[i][2]) continue;
    else dp[i][2] = 1;
}
for(int j = 2;j<=by;j++) 
{
    if(s[2][j]) continue;
    else dp[2][j] = 1;
} 
dp[2][2] = 0;
for(int i = 3;i<=bx;i++)
{
    for(int j = 3;j<=by;j++)
    {
        if (s[i][j]) continue;
        dp[i][j] = dp[i-1][j]+dp[i][j-1];
    }
}