#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, xSteps = x, ySteps = y;
	int pointY = 0, pointX = 0;
	int a = n, b = 0;
	for (int j = 1; j <= n; ++j) {
		a = 1 + ySteps; 
		b = 1 + xSteps; 
		if (pointY + a <= n && ySteps > -1) { 
			pointY += a; 
			++counterSteps;
		}
		if (pointX  + b <= m && xSteps > -1 ) {
			pointX += b; 
			++counterSteps; 
		}
		--ySteps;
		--xSteps; 
	}
	cout << counterSteps;
	return 0;
}

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