#include <bits/stdc++.h>
using namespace std;
int main(void) {
  double a, b, x;
  cin >> a >> b >> x;
  if (min(a * a * b, a * b * b) / 2 <= x) {
    double height = (2 * a * a * b - 2 * x) / (a * a);
    cout << atan(height / a) * 180 / 3.141592653689793238 << endl;
  } else {
    double height = (x * 2) / (b * a);
    cout << atan(b / height) * 180 / 3.141592653689793238 << endl;
  }
  return 0;
}
