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

int main(){
  double a,b,x,rad;
  cin>> a >> b >> x;
  if (x>=a*a*b/2.0) rad=atan(2.0*(a*a*b-x)/a/a/a);
  else rad=atan(a*b*b/2.0/x);
  printf("%.7f\n",rad/M_PI*180.0);
}