#include <bits/stdc++.h>
const long double PI = (acos(-1));
using namespace std;
int main() {
  long double a, b, x;
  cin >> a >> b >> x;
  if (a * a * b / 2 > x) {
    long double t = (a * b * b) / (2 * x);
    cout << atan(t) * 180.0 / PI << endl;
  } else {
    long double t = 2.0 * ((a * a * b - x) / (a * a * a));
    cout << atan(t) * 180.0 / PI << endl;
  }
}
