#include<iostream>
#include<cmath>
using namespace std;
int main(){
  double a,b,c;
  cin>>a>>b>>c;
  static const double pi = 3.141592653589793;
  if(c<=a*b*a/2){
    cout<<90-atan(2*c/a/b/b)/pi*180<<endl;
  }else{
    cout<<90-atan(2*(a*b*a-c)/a/a/a)/pi*180<<end;
  }
return 0;
}
