#include <bits/stdc++.h>
using namespace std;
int main() {
  double a, b, x;
  cin >> a >> b >> x;
  double tnum = (2 * a * a * b - 2 * x) / (a * a * a);
  double tnum2 = (b * b * a) / (2 * x);
  double arct = atan(tnum);
  double arct2 = atan(tnum2);
  double ans = arct * 180 / 3.14159265359;
  double ans2 = arct2 * 180 / 3.14159265359;
  if (b - x / (a * a) < x / (a * a)) {
    cout << fixed << setprecision(10) << ans << endl;
  } else {
    cout << fixed << setprecision(10) << ans2 << endl;
  }
}
