#include<bits/stdc++.h>

using namespace std;
#define INFS (1LL<<28)
#define INF (1LL<<60)
#define DEKAI 1000000007
#define MOD 998244353
#define lp(i,n) for(int i=0;i<n;i++)
#define double long double
#define all(c) begin(c), end(c)

#define int long long 
#define qhoge pair<pair<int,int>,int>
int dp[1000][1000];

namespace {
#define __DECLARE__(C)    \
    template <typename T> \
    std::ostream &operator<<(std::ostream &, const C<T> &);

#define __DECLAREM__(C)               \
    template <typename T, typename U> \
    std::ostream &operator<<(std::ostream &, const C<T, U> &);

__DECLARE__(std::vector)
__DECLARE__(std::deque)
__DECLARE__(std::set)
__DECLARE__(std::stack)
__DECLARE__(std::queue)
__DECLARE__(std::priority_queue)
__DECLARE__(std::unordered_set)
__DECLAREM__(std::map)
__DECLAREM__(std::unordered_map)

template <typename T, typename U>
std::ostream &operator<<(std::ostream &, const std::pair<T, U> &);
template <typename... T>
std::ostream &operator<<(std::ostream &, const std::tuple<T...> &);
template <typename T, std::size_t N>
std::ostream &operator<<(std::ostream &, const std::array<T, N> &);

template <typename Tuple, std::size_t N>
struct __TuplePrinter__ {
    static void print(std::ostream &os, const Tuple &t) {
        __TuplePrinter__<Tuple, N - 1>::print(os, t);
        os << ", " << std::get<N - 1>(t);
    }
};

template <typename Tuple>
struct __TuplePrinter__<Tuple, 1> {
    static void print(std::ostream &os, const Tuple &t) { os << std::get<0>(t); }
};

template <typename... T>
std::ostream &operator<<(std::ostream &os, const std::tuple<T...> &t) {
    os << '(';
    __TuplePrinter__<decltype(t), sizeof...(T)>::print(os, t);
    os << ')';
    return os;
}

template <typename T, typename U>
std::ostream &operator<<(std::ostream &os, const std::pair<T, U> &v) {
    return os << '(' << v.first << ", " << v.second << ')';
}

#define __INNER__                             \
    os << '[';                                \
    for (auto it = begin(c); it != end(c);) { \
        os << *it;                            \
        os << (++it != end(c) ? ", " : "");   \
    }                                         \
    return os << ']';

template <typename T, std::size_t N>
std::ostream &operator<<(std::ostream &os, const std::array<T, N> &c) {
    __INNER__
}

#define __DEFINE__(C)                                           \
    template <typename T>                                       \
    std::ostream &operator<<(std::ostream &os, const C<T> &c) { \
        __INNER__                                               \
    }

#define __DEFINEM__(C)                                             \
    template <typename T, typename U>                              \
    std::ostream &operator<<(std::ostream &os, const C<T, U> &c) { \
        __INNER__                                                  \
    }

#define __DEFINEW__(C, M1, M2)                                  \
    template <typename T>                                       \
    std::ostream &operator<<(std::ostream &os, const C<T> &c) { \
        std::deque<T> v;                                        \
        for (auto d = c; !d.empty(); d.pop()) v.M1(d.M2());     \
        return os << v;                                         \
    }

__DEFINE__(std::vector)
__DEFINE__(std::deque)
__DEFINE__(std::set)
__DEFINEW__(std::stack, push_front, top)
__DEFINEW__(std::queue, push_back, front)
__DEFINEW__(std::priority_queue, push_front, top)
__DEFINE__(std::unordered_set)
__DEFINEM__(std::map)
__DEFINEM__(std::unordered_map)
}

using Weight = int;
using Flow = int;
struct Edge {
    int src, dst;
    Weight weight;
    Flow cap;
    Edge() : src(0), dst(0), weight(0) {}
    Edge(int s, int d, Weight w) : src(s), dst(d), weight(w) {}
};
using Edges = std::vector<Edge>;
using Graph = std::vector<Edges>;
using Array = std::vector<Weight>;
using Matrix = std::vector<Array>;

void add_edge(Graph &g, int a, int b, Weight w = 1) {
    g[a].emplace_back(a, b, w);
    g[b].emplace_back(b, a, w);
}
void add_arc(Graph &g, int a, int b, Weight w = 1) { g[a].emplace_back(a, b, w); }

#define double long double
#define PI 3.14159265358979323846264338
signed main(){
	std::cout <<fixed<< std::setprecision(20);
	double a,b,x;
	cin>>a>>b>>x;
	x+=0.0000000000000001;
	x/=a;
	double mini=0,maxi=90;
	double dgs=90-atan(a/b)*(180/PI);
	lp(z,100){
		double l=(mini+maxi)/2;
		//cout<<l<<endl;
		double lrad=l*(PI/180);
		double ts=0;
		if(dgs<=l){
			//ts=a*b;
			double ls=l-dgs;
			ts=b*b*tan(90*(PI/180)-lrad)/2;
		}
		else{
			ts=a*b;
			ts-=a*a*tan(lrad)/2;
		}
		//cout<<ts<<endl;
		if(ts>=x){
			mini=l;
		}
		else maxi=l;
	}
	cout<<maxi<<endl;
	return 0;
}
/*
int a[1000001],b[1000001];
#define lpm(i,n) for(int i=n-1;i>=0;i--)
signed main(){
	int n;
	cin>>n;
	int k;
	cin>>k;
	vector<int> x(n);
	lp(i,n){
		cin>>x[i];
		a[x[i]]++;
	}
	lpm(i,1000001){
		if(i>=1000000)continue;
		a[i]+=a[i+1];
	}
	lpm(i,1000001){
		if(i>=1000000)continue;
		b[i]=b[i+1]+a[i+1];
	}
	sort(all(x));
	reverse(all(x));
	int tem=-1;
	lpm(i,1000001){
		if(b[i]>=k){
			tem=i;
			break;
		}
	}
	lp(i,n){
		if(x[i]>tem){
			k-=x[i]-tem;
			x[i]=tem;
		}
	}
	lp(i,n){
		if(k>=0)break;
		k++;
		x[i]++;
	}
	lp(i,n){
		cout<<x[i]<<endl;
	}
	vector<int> y(n);
	lp(i,n){
		cin>>y[i];
	}
	sort(all(y));
	sort(all(x));
	reverse(all(x));
	if(tem==-1){
		cout<<0<<endl;
		return 0;
	}
	int ans=-1;
	lp(i,n){
		ans=max(x[i]*y[i],ans);
	}
	cout<<ans<<endl;
	return 0;
}*/

Measured memory_bytes: 384