#include <bits/stdc++.h>
using namespace std;
int main(){ 
  double a,b,x;cin>>a>>b>>x;
  if(a*a*b<2*x)printf("%lf\n",180*atan((a*a*b-x)*2/a/a/a)/acos(-1));
  else printf("%lf\n",180*atan(a*b*b/2/x)/acos(-1));
}