#include <iostream>
using namespace std;
 
const int MAX_SIZE = 20;
 
int main() {
	int n, m , x, y, mt[MAX_SIZE + 1][MAX_SIZE + 1];
	cin >> n >> m >> x >> y;
	for (int i = 1; i <= n; ++i) {
		for (int j = 1; j <= m; ++j) {
			cin >> mt[i][j];
		}
	}
 
	int counterSteps = 0, ySteps = y, xSteps = x;
 
	int pointY = 0, pointX = 0;; // 1 + 3 = 4. 
	for (int i = 1; i <= n; ++i) {
 
		for (int j = 1; j <= m; ++j) {
 
			if (pointY <= n && ySteps != 0) {
				pointY = 1 + ySteps;
				--ySteps;
				++counterSteps;
				//cout << j <<" " << counterSteps <<" \n";
			}
			if (pointX <= n && xSteps != 0 && ySteps == 0) {
				pointX = 1 + xSteps;
				++counterSteps;
				--xSteps;
			}
		}
 
	}
	cout << counterSteps;
 
	return 0;
}
//https://l...content-available-to-author-only...e.ro/page/2gluma-de-1-aprilie#319648

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

NSA1IAoyIDMgCjEgMiAzIDQgNSAKMSAyIDMgNCA1IAoxIDIgMyA0IDUgCjEgMiAzIDQgNSAKMSAyIDMgNCA1IA==

5 5 
2 3 
1 2 3 4 5 
1 2 3 4 5 
1 2 3 4 5 
1 2 3 4 5 
1 2 3 4 5