#include <bits/stdc++.h>
using namespace std;
int main() {
  double pi = 3.141592;
  long double a, b, x;
  cin >> a >> b >> x;
  long double ans;
  long double u = a * a * b - x;
  long double v = a * a * a;
  if (a * b * a / 2 >= x) {
    double j = atan2l(a * b * b, (2 * x));
    ans = (j * 180) / pi;
    cout << ans << endl;
  } else {
    long double h = atan2l((2 * u), v);
    ans = (h * 180) / pi;
    cout << ans << endl;
  }
}
