/*{{{*/
//#define HOME
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
using namespace std;

#define MP make_pair
#define MT make_tuple
#define PB push_back
#define EB emplace_back
#define F first
#define S second

template<class T> void _R(T &_x) { cin >> _x; }
void _R(int &_x) { scanf("%d", &_x); }
void _R(int64_t &_x) { scanf("%" SCNd64, &_x); }
void _R(double &_x) { scanf("%lf", &_x); }
void _R(char &_x) { scanf(" %c", &_x); }
void _R(char *_x) { scanf("%s", _x); }
template<class T, class U> void _R(pair<T, U> &_x) {_R(_x.F); _R(_x.S);}
void R() {}
template<class T, class... U> void R(T &_head, U &... _tail) { _R(_head); R(_tail...); }

template<class T> void _W(const T &_x) { cout << _x; }
void _W(const int &_x) { printf("%d", _x); }
void _W(const int64_t &_x) { printf("%" PRId64, _x); }
void _W(const double &_x) { printf("%.16f", _x); }
void _W(const char &_x) { putchar(_x); }
void _W(const char *_x) { printf("%s", _x); }
template<class T, class U> void _W(const pair<T, U> &_x) {_W(_x.F); putchar(' '); _W(_x.S);}
template<class T> void _W(const vector<T> &_x) { for (auto i = _x.begin(); i != _x.end(); _W(*i++)) if (i != _x.cbegin()) putchar(' '); }
void W() {}
template<class T, class... U> void W(const T &_head, const U &... _tail) { _W(_head); putchar(sizeof...(_tail) ? ' ' : '\n'); W(_tail...); }
template<class T, class... U> void DB(const T &_head, const U &... _tail) {
#ifdef HOME
    W('#', _head, _tail...);
#endif
}

#define SZ(x) (int)((x).size())
#define ALL(x) (x).begin(), (x).end()
#define RAN(x,n) (x).begin(), (x).begin()+(n)
#define UNIQUE(x) {sort(ALL(x)); (x).erase(unique(ALL(x)), (x).end());}

#define REP(i,a,b) for (int i = (a); i <= (b); ++i)
#define REPD(i,a,b) for (int i = (a); i >= (b); --i)
#define FORI(i,n) REP(i,1,n)
#define FOR(i,n) REP(i,0,int(n)-1)
//#define ITER(i,t) for (auto i = t.begin(); i != t.end(); ++i)
#define IT3(i,st,ed) for (auto i = st; i != ed; ++i)
#define IT2(i,range) IT3(i,range)

#define MS0(X) memset((X), 0, sizeof((X)))
#define MS1(X) memset((X), -1, sizeof((X)))
#define MS(X, v) memset((X), (v), sizeof((X)))

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

typedef int64_t ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> pii;

inline int LG (const unsigned int &_x) { return 31-__builtin_clz(_x); }  // floor: LG(x), ceil: LG(x-1)+1
/*}}}*/

const double PI = acos(-1);

int a, b, x;

double bs1(double left, double right){
    FOR(iter, 50){
        double angle = (left + right) / 2;
        double volumn = a * a * a * tan(angle * PI / 180);
        // aab - volumn/2 >= x
        bool valid = volumn <= 2 * (a * a * b - x);
        if(valid) left = angle;
        else right = angle;
    }
    return (left + right) / 2;
}

double bs2(double left, double right){
    FOR(iter, 50){
        double angle = (left + right) / 2;
        double volumn = a * b * b * tan((90 - angle) * PI / 180);
        // volumn/2 >= x
        bool valid = volumn >= 2 * x;
        if(valid) left = angle;
        else right = angle;
    }
    return (left + right) / 2;
}

int main(){
    R(a, b, x);

    double mi = atan((1.0 * b) / a) / PI * 180;
    if(a * a * b == x * 2){
        W(mi);
    }else if(a * a * b < x * 2){
        // ans < atan(b/a);
        W(bs1(0, mi));
    }else{
        W(bs2(mi, 90));
    }

    return 0;
}


Measured memory_bytes: 256