import java.util.Scanner;
 
public class Main {
 
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int x = sc.nextInt();
 
    double aab_x =  a*a*b -x;
 
    double ans =0;
    if(aab_x!=0){
      double c =  2.0d * aab_x / (double)(a*a);
 
      if(c>b){
        c = (double)x *2.0d / ((double) a * b);
        ans = 90.0d-Math.toDegrees(Math.atan( (c/b)));
      }else{
        ans = Math.toDegrees(( Math.atan( c /a )));
      }
 
 
    }
    System.out.println(ans);
  }
 
}