#include <iostream>
#include <math.h>
using namespace std;
int main(void){
    double a,b,x,r,pi;
    pi=3.14159265358979;
    cin>>a>>b>>x;
    if(x*2<a*a*b){
        r=atan(a*b*b/(x*2));
    }else{
        r=atan(2*(a*a*b-x)/(a*a*a));
    }
    r=r*180/pi;
    printf("%.12f",r);
    cout<<endl;
}
