#include <iostream>
int main() {
	int b1[4], b2[4], t[4];
	int result = 0;
	scanf("%d %d %d %d", &b1[0], &b1[1], &b1[2], &b1[3]);
	scanf("%d %d %d %d", &b2[0], &b2[1], &b2[2], &b2[3]);
	scanf("%d %d %d %d", &t[0], &t[1], &t[2], &t[3]);

	result += (b1[2] - b1[0]) * (b1[3] - b1[1]);
	result += (b2[2] - b2[0]) * (b2[3] - b2[1]);

	//1st
	if (t[0] < b1[2] && t[1] < b1[3] && t[2] > b1[0] && t[3] > b1[1]) {
		int inv_w = 0; int inv_h = 0;
		//width
		if (b1[0] <= t[0]) {
			if (t[2] <= b1[2])
				inv_w = t[2] - t[0];
			else
				inv_w = b1[2] - t[0];
		}
		else {
			if (t[2] <= b1[2])
				inv_w = t[2] - b1[0];
			else inv_w = b1[2] - b1[0];
		}
		//height
		if (b1[1] <= t[1]) {
			if (t[3] <= b1[3])
				inv_h = t[3] - t[1];
			else
				inv_h = b1[3] - t[1];
		}
		else {
			if (t[3] <= b1[3])
				inv_h = t[3] - b1[1];
			else inv_h = b1[3] - b1[1];
		}

		int inv = inv_w * inv_h;
		result -= inv;
	}

	//2nd
	if (t[0] < b2[2] && t[1] < b2[3] && t[2] > b2[0] && t[3] > b2[1]) {
		int inv_w = 0; int inv_h = 0;
		//width
		if (b2[0] <= t[0]) {
			if (t[2] <= b2[2])
				inv_w = t[2] - t[0];
			else
				inv_w = b2[2] - t[0];
		}
		else {
			if (t[2] <= b2[2])
				inv_w = t[2] - b2[0];
			else inv_w = b2[2] - b2[0];
		}
		//height
		if (b2[1] <= t[1]) {
			if (t[3] <= b2[3])
				inv_h = t[3] - t[1];
			else
				inv_h = b2[3] - t[1];
		}
		else {
			if (t[3] <= b2[3])
				inv_h = t[3] - b2[1];
			else inv_h = b2[3] - b2[1];
		}

		int inv = inv_w * inv_h;
		result -= inv;
	}


	printf("%d", result);

}

#include <iostream>

using namespace std;

int arr[2002][2002];
int main() {
	// your code goes here
	int ax1, ay1, ax2, ay2;
	int bx1, by1, bx2, by2;
	int cx1, cy1, cx2, cy2;

	cin >> ax1 >> ay1 >> ax2 >> ay2 >> bx1 >> by1 >> bx2 >> by2 >> cx1 >> cy1 >> cx2 >> cy2;

	ax1 += 1000;
	ay1 += 1000;
	ax2 += 1000;
	ay2 += 1000;
	bx1 += 1000;
	by1 += 1000;
	bx2 += 1000;
	by2 += 1000;
	cx1 += 1000;
	cy1 += 1000;
	cx2 += 1000;
	cy2 += 1000;

	for(int i=ax1;i<ax2;i++){
		for(int j=ay1;j<ay2;j++){
			arr[i][j] = 1;
		}
	}
	for(int i=bx1;i<bx2;i++){
		for(int j=by1;j<by2;j++){
			arr[i][j] = 1;
		}
	}
	for(int i=cx1;i<cx2;i++){
		for(int j=cy1;j<cy2;j++){
			arr[i][j] = 2;
		}
	}
	int ans = 0;
	for(int i=0;i<=2000;i++){
		for(int j=0;j<=2000;j++){
			if(arr[i][j]==1) ans++;
		}
	}
	printf("%d", ans);
	return 0;
}