#include <iostream>
#include <cmath>
using namespace std;
int main()
{
double a, b, c, r, p;
cin >> a >> b >> c;
if ((a + b >= c) && (a + c >= b) && (b + c >= a))
{
p= (a+b+c)/2;
r = (sqrt(p * ((p - a) * (p - b) * (p - c)))) / p * 100;
if (int(r) % 10 == 0)
{
if (int(r) / 10 % 10 == 0)
cout << int(r) / 100 << ".00";
else
cout << int(r) / 100 << '.' << int(r) / 10 % 10 << 0;
}
else
cout << int(r) / 100 << '.' << int(r) / 10 % 10 << int(r) % 10;
}
else
cout << "Imposibil";
return 0;
}
