#include <bits/stdc++.h>
using namespace std;

int main(){
  double a, b, x;
  cin >> a >> b >> x;
  double vol = a*a*b;
  double ans = 0;
  if (vol/2 < x){
    ans = atan((2*a*a*b-2*x)/(a*a*a));
  }
  else {
    ans = M_PI/2 - atan(2*x/(a*b*b));
  }
  cout << setprecision(10);
  cout << ans*180/M_PI << endl;
}
