#include <bits/stdc++.h>
using namespace std;
const long double PI = acos(-1);
int main(void) {
  int a, b, x;
  cin >> a >> b >> x;
  long double ans;
  double ref = a * a * b / 2;
  if (x <= ref) {
    int bunsi = a * b * b;
    int bunbo = 2 * x;
    long double bunsuu = bunsi / bunbo;
    ans = atan(bunsuu) * 180 / PI;
  } else if (x <= a * a * b) {
    int bunsi = 2 * (a * a * b - x);
    int bunbo = a * a * a;
    long double bunsuu = bunsi / bunbo;
    ans = atan(bunsuu) * 180 / PI;
  }
  cout << fixed << setprecision(10) << ans << endl;
  return 0;
}
