#include <bits/stdc++.h>
using namespace std;
int main() {
  float a, b, x;
  cin >> a >> b >> x;
  float v = a * a * b;
  float s = a * b;
  float y = x / a;
  float tan;
  float ans;
  if (v >= 2 * x) {
    tan = b * b / (2 * y);
    ans = atan(tan);
    ans = ans * 180 / 3.141592653589793238;
  } else {
    y = s - y;
    tan = 2 * y / (a * a);
    ans = atan(tan);
    ans = ans * 180 / 3.141592653589793238;
  }
  cout << setprecision(10) << ans << endl;
}
