#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  const long double PI = acos(-1);
  long double a, b, x;
  cin >> a >> b >> x;
  long double theta;
  if (x < a * a * b / 2.0)
    theta = atan((a * b * b) / 2 / x);
  else
    theta = atan((2 * (a * a * b - x) / a / a / a));
  cout << setprecision(10) << fixed << theta * 180.0 / PI;
  cerr << "\nTime elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
}
