#include <bits/stdc++.h>
using namespace std;
int main() {
  double a, b, x;
  cin >> a >> b >> x;
  double v = a * a * b;
  double s = a * b;
  double y = x / a;
  double tan;
  double ans;
  if (v >= 2 * x) {
    tan = b * b / (2 * y);
    ans = atan(tan);
    ans = ans * 180 / 3.14159265358979;
  } else {
    y = s - y;
    tan = 2 * y / (a * a);
    ans = atan(tan);
    ans = ans * 180 / 3.14159265358979;
  }
  cout << setprecision(10) << ans << endl;
}
