#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int cx[3], cy[3], rx[3], ry[3];

int rxp[3], ryp[3];

int POINTS = 10000000;
int INF = 1000000;
int r;
double rr;
inline double getRandCoord()
{
	r = rand() % 1048576;
	r -= 524288;
	rr = r;
	rr /= 524288;
	return rr;
}

int main() {
	srand(time(0));

	freopen("geo.in", "rt", stdin);

	int minx = INF, miny = INF, maxx = -INF, maxy = -INF;
	double varx, vary, midx, midy;

	for (int i = 0; i < 3; i++) {
		scanf("%d %d %d %d", &cx[i], &cy[i], &rx[i], &ry[i]);
		rxp[i] = rx[i] * rx[i];
		ryp[i] = ry[i] * ry[i];

		if (minx > cx[i] - rx[i]) {
			minx = cx[i] - rx[i];
		}

		if (miny > cy[i] - ry[i]) {
                        miny = cy[i] - ry[i];
                }
		if (maxx < cx[i] + rx[i]) {
                        maxx = cx[i] + rx[i];
                }
		if (maxy < cy[i] + ry[i]) {
                        maxy = cy[i] + ry[i];
                }
	}
	varx = (maxx - minx) / 2;
	vary = (maxy - miny) / 2;
	midx = (minx + maxx) / 2;
	midy = (miny + maxy) / 2;

	int insidePt = 0;
	int in, j;
	double xx, yy, xxx, yyy;
	for (int i = 0; i < POINTS; i++) {

		xxx = getRandCoord();
		xxx = midx + varx * xxx;
		yyy = getRandCoord();
		//printf("%6lf\n", yyy);
		yyy = midy + vary * yyy;

		in = 0;
		for (j = 0; j < 3 && !in; j++) {

			xx = xxx - cx[j];
		        yy = yyy - cy[j];

		        if (xx * xx * ryp[j] + yy * yy * rxp[j] <=  rxp[j] * ryp[j] + 0.00001) { //ry[j] * ry[j] * rx[j] * rx[j]) {
				in = 1;
			}
		}

		insidePt += in;
		//printf("%.5lf\n", r);
	}

	double v = (maxx - minx) * (maxy - miny);

	//printf("%d  /  %d \n", insidePt, POINTS);
	v *= insidePt;
	v /= POINTS;

	printf("%.6lf\n", v);


	
	return 0;
}