i thought i've solved this problem, but getting WA when i submit this
anyone can help me?

include

include

define pi 3.14159265

using namespace std;
int main()
{
double n,f,l,r;
cin>>n;
while (n!=0)
{
if (1<=n<=100)
{
l = (0.5*n*n)/pi;

                cout << setprecision(2) << l << endl;
                cin>>n;
            }
    }

}