#include<iostream>
#include<math.h>
#include <iomanip>

using namespace std;

int main(){
  long double a,b,x;
  long double y;
  cin >> a >> b >> x;
  if(x >= a * a * b / 2) y = atan(2*b/a-2*x/a/a/a);
    else y = atan((a*b*b)/(2*x));
      cout << setprecision(10) << y * 180 / 3.14159265358979323;
}