I have no idea why I have CE on this solution. Can anyone help me?

#include <iostream>
#include <stdio.h>
#include <math.h>
#include <algorithm>
using namespace std;

long double eps = 1e-4;

int main ()
{
    double r, l, sq;
    cin>>l>>r;
    if (2*r <= l)
    {
        sq = M_PI*r*r;
    }
    else if (l*l <= 2*r*r)
    {
        sq = l*l;
    }
    else
    {
        double cs = (l/2)/r, angle;
        angle = acos (cs);
        sq = r*l/2*sin (angle);
        angle *= 8, sq *= 4;
        double sq2 = (2*M_PI-angle)*r*r/2;
        if (sq2 < eps)
        {
            sq -= sq2;
        }
        else
        {
            sq += sq2;
        }
    }
    printf ("%.3lf", sq);
    return 0;
}

It was my problem too.
just use 3.1415... instead of M_PI.
M_PI is not declared for the INTEL compiler.