#include<bits/stdc++.h>

using namespace std;


int main(){
  const double PI = acos(-1.0);
  double a, b, x;
  cin >> a >> b >> x;
  
  x /= a;
  
  cout << fixed << setprecision(10);
  if(x>a*b/2) cout << atan2((a*b-x)*2, a*a) * 180 / PI << endl;
  else cout << atan2(b*b, x*2) * 180 / PI << endl;
  
  
  return 0;
}