#include <bits/stdc++.h>
constexpr double PI = 3.1415926535;
int main() {
  using namespace std;
  long double a, b, x;
  cin >> a >> b >> x;
  long double S = x / a;
  long double B = a * b / 2;
  if (S > B) {
    long double n = 2 * S / a - b;
    long double t = atanl((b - n) / a);
    cout << t * 180 / M_PI << endl;
  } else {
    long double n = 2 * S / b;
    long double t = atanl(b / n);
    cout << t * 180 / M_PI << endl;
  }
}
