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#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define Pi 3.1415926535898
//两线段交点
void GetCrossPoint(double *x, double *y, double x1, double y1, double x2,
double y2, double x3, double y3, double x4, double y4) //四点交点坐标
{
//1 3 一条直线，2，4一条
double x_,y_;
/*
if (x1==x3)
{
x_=x1;
y_=(x1-x4)*(y2-y4)/(x2-x4)+y4;
}
if (x1==x3)
{
x_=x2;
y_=(x2-x1)*(y3-y1)/(x3-x1)+y1;
}
else
{
x_ = ((y1 - y2) - x1 *(y3 - y1) / (x3 - x1) + x2 *(y4 - y2) / (x4 - x2)
) / ((y4 - y2) / (x4 - x2) - (y3 - y1) / (x3 - x1));
y_ = (x_ - x2)*(y4 - y2) / (x4 - x2) + y2;
}
*x = x_;
*y = y_;
*/
//根据两点式化为标准式，进而求线性方程组
double tempLeft,tempRight;
//求x坐标
tempLeft = (x2 - x4) * (y1 - y3) - (x3 - x1) * (y4 - y2);
tempRight = (y1 - y4) * (x3 - x1) * (x2 - x4) + x4 * (y2 - y4) * (x3 - x1) - x1 * (y3 - y1) * (x2 - x4);
x_ =tempRight /tempLeft;
//求y坐标
tempLeft = (x1 - x3) * (y2 - y4) - (y3 - y1) * (x4 - x2);
tempRight = y3 * (x1 - x3) * (y2 - y4) + (x2- x3) * (y2 - y4) * (y1 - y3) - y2 * (x4 - x2) * (y3 - y1);
y_ =tempRight / tempLeft;
*x = x_;
*y = y_;
}
//由三点坐标得出面积
double GetAreaByThirePoint(double x1, double y1, double x2, double y2, double x3,double y3)
{
double a = x2 - x1;
double b = y2 - y1;
double c = x3 - x1;
double d = y3 - y1;
return 0.5 *fabs(a *d - b * c);
}
//排序
void BubbleSort(int *pData, int Count)
{
int iTemp;
for (int i = 1; i < Count; i++)
{
for (int j = Count - 1; j >= i; j--)
{
if (pData[j] < pData[j - 1])
{
iTemp = pData[j - 1];
pData[j - 1] = pData[j];
pData[j] = iTemp;
}
}
}
}
int main()
{
int N, *b;
double *a;
int i = 0, j = 0;
int sum = 0;
N = 5;
//scanf("%d", &N);
b = (int*)malloc(5 *sizeof(int*));//角度制下的输入角度
a = (double*)malloc(5 *sizeof(double*));//被转化后的弧度
///--------------------0 144 72 288 216
//b[0]=1; b[1]=73; b[2]=145; b[3]=289; b[4]=217;
/* b[0]=90; b[1]=270; b[2]=45; b[3]=315; b[4]=0;
//Max=23;
for (i = 0; i < 5; i++)
{
b[i] = b[i] -1;
}
*/
for (i = 0; i < 5; i++)
{
scanf("%d", b + i);
}
//三角形面积：
BubbleSort(b, 5);
for (i = 0; i < 5; i++)
{
a[i] = b[i] *2 * Pi / 360;
}
//double aa = GetAreaByThirePoint(0, 0, 1, 0, 0, 1);
double v1, v2;
GetCrossPoint(&v1, &v2, 0, 0, 1, 0, 1, 1, 0, 1);
GetCrossPoint(&v1, &v2, 0, 0, 1, 0, 1, 1, 0, 1);
double x[6], y[6], Trigon[6], Fan[6];
x[0] = cos(a[0]); y[0] = sin(a[0]);
x[1] = cos(a[1]); y[1] = sin(a[1]);
x[2] = cos(a[2]); y[2] = sin(a[2]);
x[3] = cos(a[3]); y[3] = sin(a[3]);
x[4] = cos(a[4]); y[4] = sin(a[4]);
double Left_x, Left_y, Right_x, Righ_y;
for (i = 0; i < 5; i++)
{
GetCrossPoint(&Left_x, &Left_y, x[(0+i) % 5], y[(0+i) % 5], x[(1+i) % 5], y[(1+i) % 5], x[(2+i) % 5], y[(2+i) % 5], x[(4+i) % 5], y[(4+i) % 5]);
GetCrossPoint(&Right_x, &Righ_y, x[(0+i) % 5], y[(0+i) % 5], x[(1+i) % 5], y[(1+i) % 5], x[(3+i) % 5], y[(3+i) % 5], x[(4+i) % 5], y[(4+i) % 5]);
Trigon[i] = GetAreaByThirePoint(x[(i) % 5], y[(i) % 5], Left_x, Left_y, Right_x,Righ_y);
double temp = a[i % 5] - a[(1+i) % 5];
if (temp > Pi)
{
temp = Pi*2 - temp;
}
else
temp = - 1 * temp;
Fan[i] = 0.5 *(temp) - GetAreaByThirePoint(0.0, 0.0, x[(i) % 5], y[(i) % 5],x[(1+i) % 5], y[(1+i) % 5]) + GetAreaByThirePoint(Left_x, Left_y, x[(i) % 5], y[(i) % 5], x[(1+i) % 5], y[(1+i) % 5]);
} //求三角，弓形面积
double AllEquation = 0.0, Alltrigon = 0.0;
double LastArea = 0.0;//最后的中心的面积
for (i = 0; i < 5; i++)
{
LastArea += Trigon[i] + Fan[i];
} //求中心面积
LastArea = Pi - LastArea;
for (i = 0; i < 5; i++)
{
Alltrigon += (Trigon[i] - Pi / 11)*(Trigon[i] - Pi / 11);
AllEquation += (Fan[i] - Pi / 11)*(Fan[i] - Pi / 11);
}
double result = (Alltrigon + AllEquation + (LastArea - Pi / 11)*(LastArea -Pi / 11)) / 11;
result = (double)((int)(result*10000+0.5))/10000.0;
printf("%0.4f\n", result);
return 0;
}
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