include

include

include

define Maxsize 1001

using namespace std;
int main()
{
int a[Maxsize][Maxsize] = {0};
int n, m, r, c;
cin >> n >> m >> r >> c;
int n1=1, n2=n, m1=1, m2=m;
int x = 1, y = 1, sum = 1;
while (sum <= n * m)
{
while (sum<= n * m && y < m2)
{
a[x][y] = sum++;
y++;
}

    while (sum <= n * m && x < n2)
    {
        a[x][y] = sum++;
        x++;
    }

    while (sum <= n * m && y > m1)
    {
        a[x][y] = sum++;
        y--;
    }

    while (sum <= n * m && x > n1)
    {
        a[x][y] = sum++;
        x--;
    }
    n1++; n2--; m1++; m2--;
    x++; y++;
    if (sum == n * m)
        a[x][y] == sum++;
}
if (m == n && m % 2 == 1)
    a[m / 2 + 1][m / 2 + 1] = n * m;
cout << a[r][c];
return 0;

}