// Original C++ solution (slower):
#include <bits/stdc++.h>

using namespace std;

using ll=long long;

using ld=long double;

using ull=unsigned long long;

using uint=unsigned int;

using pcc=pair<char,char>;

using pii=pair<int,int>;

using pll=pair<ll,ll>;

using pdd=pair<double,double>;

using tuplis=pair<ll,pll>;

using tuplis2=pair<pll,ll>;

template<class T> using pq=priority_queue<T,vector<T>,greater<T>>;

const ll LINF=0x1fffffffffffffff;

const ll MINF=0x7fffffffffff;

const int INF=0x3fffffff;

const ll MOD=1000000007;

const ll MODD=998244353;

const ld DINF=numeric_limits<ld>::infinity();

const ld EPS=1e-9;

const ld PI=3.141592653589793238462643383279;

const vector<ll>four{0,1,0,-1,0};

#define _overload4(_1,_2,_3,_4,name,...) name

#define _overload3(_1,_2,_3,name,...) name

#define _rep1(n) for(ll i=0;i<n;++i)

#define _rep2(i,n) for(ll i=0;i<n;++i)

#define _rep3(i,a,b) for(ll i=a;i<b;++i)

#define _rep4(i,a,b,c) for(ll i=a;i<b;i+=c)

#define rep(...) _overload4(__VA_ARGS__,_rep4,_rep3,_rep2,_rep1)(__VA_ARGS__)

#define _rrep1(n) for(ll i=(n)-1;i>=0;i--)

#define _rrep2(i,n) for(ll i=(n)-1;i>=0;i--)

#define _rrep3(i,a,b) for(ll i=(b)-1;i>=(a);i--)

#define _rrep4(i,a,b,c) for(ll i=a+(b-a-1)/c*c;i>=a;i-=c)

#define rrep(...) _overload4(__VA_ARGS__,_rrep4,_rrep3,_rrep2,_rrep1)(__VA_ARGS__)

#define each(i,a) for(auto &i:a)

#define sum(...) accumulate(range(__VA_ARGS__),0LL)

#define dsum(...) accumulate(range(__VA_ARGS__),double(0))

#define _range(i) (i).begin(),(i).end()

#define _range2(i,k) (i).begin(),(i).begin()+k

#define _range3(i,a,b) (i).begin()+a,(i).begin()+b

#define range(...) _overload3(__VA_ARGS__,_range3,_range2,_range)(__VA_ARGS__)

#define _rrange(i) (i).rbegin(),(i).rend()

#define _rrange2(i,k) (i).rbegin(),(i).rbegin()+k

#define _rrange3(i,a,b) (i).rbegin()+a,(i).rbegin()+b

#define rrange(...) _overload3(__VA_ARGS__,_rrange3,_rrange2,_rrange)(__VA_ARGS__)

#define elif else if

#define unless(a) if(!(a))

#define mp make_pair

#define mt make_tuple

#define INT(...) int __VA_ARGS__;in(__VA_ARGS__)

#define LL(...) ll __VA_ARGS__;in(__VA_ARGS__)

#define ULL(...) ull __VA_ARGS__;in(__VA_ARGS__)

#define STR(...) string __VA_ARGS__;in(__VA_ARGS__)

#define CHR(...) char __VA_ARGS__;in(__VA_ARGS__)

#define DBL(...) double __VA_ARGS__;in(__VA_ARGS__)

#define vec(type,name,...) vector<type> name(__VA_ARGS__)

#define VEC(type,name,size) vector<type> name(size);in(name)

#define vv(type,name,h,...) vector<vector<type>>name(h,vector<type>(__VA_ARGS__))

#define VV(type,name,h,...) vector<vector<type>>name(h,vector<type>(__VA_ARGS__));in(name)

#define vvv(type,name,h,w,...) vector<vector<vector<type>>>name(h,vector<vector<type>>(w,vector<type>(__VA_ARGS__)))

inline constexpr ll gcd(ll a,ll b){if(!a||!b)return 0;while(b){ll c=b;b=a%b;a=c;}return a;}

inline constexpr ll lcm(ll a,ll b){if(!a||!b)return 0;return a*b/gcd(a,b);}

template<class T> inline constexpr T min(vector<T> &v){return *min_element(range(v));}

inline char min(string &v){return *min_element(range(v));}

template<class T> inline constexpr T max(vector<T> &v){return *max_element(range(v));}

inline char max(string &v){return *max_element(range(v));}

inline constexpr ll intpow(ll a,ll b){ll ans=1;for(ll i=1;b;i*=2){if(b&i){b^=i;ans*=a;}a*=a;}return ans;}

template<typename T>

inline constexpr bool chmin(T &mn,const T &cnt){if(mn>cnt){mn=cnt;return 1;}else return 0;}

template<typename T>

inline constexpr bool chmax(T &mx,const T &cnt){if(mx<cnt){mx=cnt;return 1;}else return 0;}

template<class T> unordered_map<T,ll> press(vector<T> &a){ auto b = a; sort(range(b)); b.erase(unique(range(b)), b.end()); unordered_map<T,ll> ans; rep(b.size()) ans[b[i]] = i; each(i, a) i = ans[i]; return ans; }

template<class T> map<T,ll> press_map(vector<T> &a){ auto b = a; sort(range(b)); b.erase(unique(range(b)), b.end()); map<T,ll> ans; rep(b.size()) ans[b[i]] = i; each(i, a) i = ans[i]; return ans; }

inline int scan(){ return getchar(); }

inline void scan(int &a){ scanf("%d", &a); }

inline void scan(unsigned &a){ scanf("%u", &a); }

inline void scan(long &a){ scanf("%ld", &a); }

inline void scan(long long &a){ scanf("%lld", &a); }

inline void scan(unsigned long long &a){ scanf("%llu", &a); }

inline void scan(char &a){ cin >> a; }

inline void scan(float &a){ scanf("%f", &a); }

inline void scan(double &a){ scanf("%lf", &a); }

inline void scan(long double &a){ scanf("%Lf", &a); }

inline void scan(vector<bool> &vec){ for(unsigned i = 0; i < vec.size(); i++) { int a; scan(a); vec[i] = a; } }

inline void scan(char a[]){ scanf("%s", a); }

inline void scan(string &a){ cin >> a; }

template<class T> inline void scan(vector<T> &vec);

template<class T, size_t size> inline void scan(array<T, size> &vec);

template<class T, class L> inline void scan(pair<T, L> &p);

template<class T, size_t size> inline void scan(T (&vec)[size]);

template<class T> inline void scan(vector<T> &vec){ for(auto &i : vec) scan(i); }

template<class T, size_t size> inline void scan(array<T, size> &vec){ for(auto &i : vec) scan(i); }

template<class T, class L> inline void scan(pair<T, L> &p){ scan(p.first); scan(p.second); }

template<class T, size_t size> inline void scan(T (&vec)[size]){ for(auto &i : vec) scan(i); }

template<class T> inline void scan(T &a){ cin>>a; }

inline void in(){}

template <class Head, class... Tail> inline void in(Head &head, Tail&... tail){ scan(head); in(tail...); }

inline void print(){ putchar(' '); }

inline void print(const bool &a){ printf("%d", a); }

inline void print(const int &a){ printf("%d", a); }

inline void print(const unsigned &a){ printf("%u", a); }

inline void print(const long &a){ printf("%ld", a); }

inline void print(const long long &a){ printf("%lld", a); }

inline void print(const unsigned long long &a){ printf("%llu", a); }

inline void print(const char &a){ printf("%c", a); }

inline void print(const char a[]){ printf("%s", a); }

inline void print(const float &a){ printf("%.15f", a); }

inline void print(const double &a){ printf("%.15f", a); }

inline void print(const long double &a){ printf("%.15Lf", a); }

inline void print(const string &a){ each(i, a) print(i); }

template<class T> void print(const vector<T> &vec);

template<class T, size_t size> void print(const array<T, size> &vec);

template<class T, class L> void print(const pair<T, L> &p);

template<class T, size_t size> inline void print(const T (&vec)[size]);

template<class T> void print(const vector<T> &vec){ if(vec.empty()) return; print(vec[0]); for(auto i = vec.begin(); ++i != vec.end(); ){ putchar(' '); print(*i); } }

template<class T, size_t size> void print(const array<T, size> &vec){ print(vec[0]); for(auto i = vec.begin(); ++i != vec.end(); ){ putchar(' '); print(*i); } }

template<class T, class L> void print(const pair<T, L> &p){ print(p.first); putchar(' '); print(p.second); }

template<class T, size_t size> inline void print(const T (&vec)[size]){ print(vec[0]); for(auto i = vec; ++i != end(vec); ){ putchar(' '); print(*i); } }

template<class T> inline void print(const T &a){ cout << a; }

inline int out(){ putchar('\n'); return 0; }

template<class T> inline int out(const T &t){ print(t); putchar('\n'); return 0; }

template<class Head, class... Tail> inline int out(const Head &head, const Tail&... tail){ print(head); putchar(' '); out(tail...); return 0; }

template <class T> inline void err(T t){cerr<<t<<'\n';}

template<class Head, class... Tail> inline void err(const Head &head, const Tail&... tail){ cerr<<head<<' '; err(tail...); }

inline void err(){cerr<<'\n';}

inline int first(const bool &i){return out(i?"first":"second");}

inline int yes(const bool &i){return out(i?"yes":"no");}

inline int Yes(const bool &i){return out(i?"Yes":"No");}

inline int YES(const bool &i){return out(i?"YES":"NO");}

inline int Yay(const bool &i){return out(i?"Yay!":":(");}

inline int Possible(const bool &i){return out(i?"Possible":"Impossible");}

inline int POSSIBLE(const bool &i){return out(i?"POSSIBLE":"IMPOSSIBLE");}

inline void Case(ll i){printf("Case #%lld: ",i);}







signed main(){

    LL(a,b,x);

    auto check=[&a,&b,&x](ld theta){

        ld rad=theta/180*PI;

        ld v;

        if(tan(rad)<=ld(b)/a)v=ld(a*a*b)-a*a*a*tan(rad)/2;

        else v=b*a*b/tan(rad)/2;

        return x<=v;

    };

    ld ok=0,ng=90,cen;

    rep(1000){

        cen=(ok+ng)/2;

        if(check(cen))ok=cen;

        else ng=cen;

    }

    out(ok);

}








// Optimized solution to the same problem (faster):
#include <bits/stdc++.h>

using namespace std;

using ll = long long;

const double PI = 3.141592653589;



int main(){

  cout << fixed << setprecision(20);

  ll a, b, x;

  cin >> a >> b >> x;

  if(a * a * b >= x * 2){ // 三角柱の形 a * b * b / tan(theta) / 2

    double tanx = a * b * b / 2.0 / x;

    cout << atan(tanx) * 180 / PI << endl;

  }

  else{ // 直方体 - 三角柱の形 a * a * b - a * a * atan(theta) / 2

    double tanx = 2.0 * (a * a * b - x) / a / a / a;

    cout << atan(tanx) * 180 / PI << endl;

  }

}


// Fastest known solution for this problem: