#include <bits/stdc++.h>
using namespace std;
int main() {
  double a, b, x;
  cin >> a >> b >> x;
  if (x / (a * b * a) > 1 / 2.0) {
    cout << setprecision(8)
         << (180 * atan(-2 * x / pow(a, 3) + 2 * b / a) / M_PI) << endl;
  } else {
    cout << setprecision(8) << (180 * atan(pow(b, 2) * a / (2 * x)) / M_PI)
         << endl;
  }
}
