#include <bits/stdc++.h>
using namespace std;
int main()
{
  double a,b,x,theta;
  cin>>a>>b>>x;
  if(a*a*b>2*x)theta=M_PI/2.0-atan(2*x/(a*b*b));
  else theta=atan(2*(a*a*b-x)/(a*a*a));
  cout<<fixed<<setprecision(10)<<theta*180/(M_PI)<<endl;
}