#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

double pi = 3.14159265358979;

int main(){
  double a, b, x;
  cin >> a >> b >> x;
  cout << setprecision(14);
  if(x>=a*a*b/2)cout << atan(2*b/a-2*x/(a*a*a))*180/pi;
  else cout << atan(a*b*b/(2*x))*180/pi;
  return 0;
}