
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#define LL long long int
using namespace std;int main()
{
    int a,b,x;
    scanf("%d%d",&a,&b);
    scanf("%d",&x);
    double A=a,B=b,X=x,ans;
    if(X<A*A*B/2.0)ans=atan(A*B*B/2.0/X)/pi*180;
    else ans=atan(2*(A*A*B-X)/A/A/A)/pi*180;
    printf("%.10f\n",ans);
    return 0;
}