#include <bits/stdc++.h>
#include <cctype>
#include <cstdlib>
#include <iostream>
#include <pthread.h>
#include <vector>

void one_piece() {
  std::cin.tie(0);
  std::cin.sync_with_stdio(0);
  std::cout.tie(0);
  std::cout.sync_with_stdio(0);
}


int main() {
    one_piece();

    int n, m, r, c;
    std::cin >> n >> m >> r >> c;

    int sum = 0;
    int empty = ((r-1)*m) + c;

    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            int id = ((i-1)*m) + j;
            if(id > empty) {
                if(id%m == 1) {
                    int newr = i - 1;
                    long long distance = std::abs(i - newr) + std::abs(j - m);
                    sum += distance;
                } else {
                    int newc = j - 1;
                    long long distance = std::abs(i - i) + std::abs(j - newc);
                    sum += distance;
                }
                empty = id;
            }
        }
    }

    std::cout << sum;


    return 0;
}