#include <bits/stdc++.h>
using namespace std;
float angle(float a, float b, float x) {
  float volume = a * a * b;
  if (x < volume / 2.0) {
    return M_PI / 2 - atan(2.0 * x / a * b * b);
  } else {
    return atan(2.0 * (volume - x) / (a * a * a));
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  float a, b, x;
  cin >> a >> b >> x;
  cout << fixed << setprecision(10) << angle(a, b, x) * 180.0 / M_PI << '\n';
  return 0;
}
