#include <iostream>
using namespace std;
int main() {
int n, m, x, y;
cin >> n >> m >> x >> y;
x--, y--;
int *arr = new int[n * m];
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
arr[i * m + j] = (i % 2 == 0 ? i * m + j : i * m + m - j - 1);
}
}
cout << endl << arr[x * m + y];
return 0;
}
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