#include <bits/stdc++.h>
using namespace std;
const int INF = 100000000;
const long INF64 = 1000000000000000ll;
const long long MOD = 1000000007ll;
int main() {
  double a, b, x;
  std::cin >> a >> b >> x;
  if (x <= a * a * b / 2)
    std::cout << std::setprecision(10) << atan(a * b * b / x / 2) * 180 / M_PI
              << std::endl;
  else {
    std::cout << std::setprecision(10)
              << atan(2 * (a * a * b - x) / a / a / a) * 180 / M_PI
              << std::endl;
  }
}
