#include <bits/stdc++.h>
using namespace std;
int main() {
  double a, b, x;
  cin >> a >> b >> x;
  const double pai = 3.1415926535897932;
  if (a * a * b / 2.0 <= x) {
    const double m = 2 * (a * a * b - x) / (a * a);
    cout << fixed << setprecision(12) << atan(m / a) * 180.0 / pai << endl;
  } else {
    const double m = 2 * x / (a * b);
    cout << fixed << setprecision(12) << atan(b / m) * 180.0 / pai << endl;
    ;
  }
}
