#include <bits/stdc++.h>
using namespace std;
int main(){
  double a,b,x;
  cin >>a >>b >>x;
  if(x>a*a*b/2){
    double leng=(a*b-x/a)*2/a;
    printf("%.8f",atan(leng/a)/M_PI*180);
  }
  else{
    double leng=(x/a)*2/b;
    cerr <<leng<<endl;
    double ans=atan(b/leng);
    printf("%.8f",ans/M_PI*180);
  }
}