#include <bits/stdc++.h>
#include <boost/algorithm/string/join.hpp>
#include <boost/range/irange.hpp>
#include <boost/multiprecision/cpp_int.hpp>
using namespace std;
using boost::irange;
using boost::algorithm::join;

typedef long long ll;
typedef unsigned long long ull;
//typedef long double ld;

typedef map<int, int> mii;
typedef pair<int, int> pii;
typedef pair<double,double> pdd;
typedef set<int> si;
typedef set<ll> sll;
typedef vector<int> vi;
typedef vector<pair<int, int > > vii;
typedef vector<ll> vll;
typedef vector<double> vd;
typedef vector<vi> vvi;
typedef vector<vii> vvii;
typedef vector<vll> vvll;

constexpr ll MOD = 1e9+7;
template<typename T>constexpr auto inf=numeric_limits<T>::max()/4;
constexpr int INF=inf<int>;
constexpr ll LINF=inf<ll>;

#define Sort(x) sort(begin(x),end(x))
#define Reverse(x) reverse(begin(x),end(x))
#define ABS(a,b) ((a)<(b)?(b)-(a):(a)-(b))
#define nbit(n) (1ull<<(n))
#define _ol3(_1,_2,_3,name,...)name
#define _rep(i,n)_repi(i,0,n)
#define _repi(i,a,b)for(int i=a,i##_l=(b);i<i##_l;++i)
#define REP(...) _ol3(__VA_ARGS__,_repi,_rep,)(__VA_ARGS__)
#define REPR(i,n) for(int i=n-1;i>=0;--i)
#define REPA(i,v) REP(i,(v).size())

// sort(begin(x), end(x), greater<ll>());
// lower_bound(a.begin(), a.end(), val): a[i] ≥ valである最左の位置
// upper_bound(a.begin(), a.end(), val): a[i] > valである最左の位置

// Returns minimum of a and b.
// If a is less b, a is set to b.
template<typename T>
T chmin(T& a, T b) {
  if (a > b) {
    a = b;
  }
  return a;
}

// Returns maximum of a and b.
// If a is less b, a is set to b.
template<typename T>
T chmax(T& a, T b) {
  if (a < b) {
    a = b;
  }
  return a;
}

template <typename T>
void dumpContents(const T& v, const string& msg)
{
  cerr << "### " << msg << " ###\n";
  for (const auto& x : v) {
    cerr << x << " ";
  }
  cerr << endl;
}

struct before_main_function {
  before_main_function() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout<<setprecision(20)<<fixed;
    #define endl "\n"
  }
} before_main_function;

// ========== end of template ==========
const double PI = std::acos(-1);

double A, B, X;
typedef std::function<double(double)> volume_f;

double vlarge(double r /*radian*/) {
  return A*A*(2.0*B-A*tan(r))/2.0;
}

double vsmall(double r /*radian*/) {
  return A*B*B/2.0/tan(r);
}

double binary_search(int count, double s, double e, volume_f f) {
  //cerr << "count " << count << " [" << s << ", " << e << ")" << endl;
  assert(s <= e);

  double m = (s+e)/2.0;
  if (count <= 0) {
    //cerr << "m " << m << endl;
    return m;
  }

  double mv = f(m);
  //cerr << "mv " << mv << endl;
  if (X < mv) {
    return binary_search(count-1, m, e, f);
  } else {
    return binary_search(count-1, s, m, f);
  }
}


int main(int argc, char** argv) {
  cin >> A >> B >> X;

  double boarder = A*A*B/2;

  int count = 30;
  double ret = 0; // radian
  if (boarder < X) {
//cerr << "LARGE" << endl;
    double s = 0;
    double e = atan(B/A);
    ret = binary_search(count, s, e, vlarge);
  } else {
//cerr << "SMALL" << endl;
    double s = atan(B/A);
    double e = PI/2;
    ret = binary_search(count, s, e, vsmall);
//cerr << "ret " << ret << endl;
  }

  cout << (ret/PI*180) << endl;

  return 0;
}


Measured memory_bytes: 256