#include <bits/stdc++.h>

#define PI acos(-1)
#define all(a) a.begin(), a.end()
#define full(a, n) a, a + n
#define ma(type, size) (type *)malloc(sizeof(type) * size)
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define MT make_tuple
#define f0(i, n) for (i = 0; i < (n); i++)
#define f1(i, n) for (i = 1; i < (n); i++)
#define f1n(i, n) for (i = 1; i <= (n); i++)
#define fab(i, a, b) for (i = (a); i <= (b); i++)
#define fr(i, b, a) for (i = (b); i >= (a); i--)

using namespace std;

/*
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
typedef tree<int,null_type,less<int>,rb_tree_tag,
	tree_order_statistics_node_update> indexed_set;
//*/
typedef long long int ll;
typedef long int lo;

typedef vector<ll> vll;
typedef pair<ll, ll> pll;
typedef tuple<ll, ll, ll> tll;

//* utility function
inline bool compare(ll i, ll j)
{
    return i > j;
}
//*/

//* function prototypes
template< typename T>
T gcd(T a, T b);
template< typename T>
T modpow(T number, T power, T mod_value);
//*/

//int row, column;
//int dx[8] = {1, 1, 0, -1, -1, -1, 0, 1};
//int dy[8] = {0, -1, -1, -1, 0, 1, 1, 1};
//int dx[4] = {1,  0, -1, 0};
//int dy[4] = {0, -1,  0, 1};
//ll p2[63] = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728, 268435456, 536870912, 1073741824, 2147483648, 4294967296, 8589934592, 17179869184, 34359738368, 68719476736, 137438953472, 274877906944, 549755813888, 1099511627776, 2199023255552, 4398046511104, 8796093022208, 17592186044416, 35184372088832, 70368744177664, 140737488355328, 281474976710656, 562949953421312, 1125899906842624, 2251799813685248, 4503599627370496, 9007199254740992, 18014398509481984, 36028797018963968, 72057594037927936, 144115188075855872, 288230376151711744, 576460752303423488, 1152921504606846976, 2305843009213693952, 4611686018427387904};
#ifdef DEBUG
#endif // DEBUG

int main()
{
    //ios::sync_with_stdio(0);
    //cin.tie(0);
    //cout.tie(0);
    //freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);

    ll number_of_test_case = 1, test_case;
    //cin >> number_of_test_case;
    for (test_case = 1; test_case <= number_of_test_case; test_case++)
    {
        double  i, j, k, n, a, h, x;

        cin >> a >> h >> x;

        double b = x/(h*a/2);
        double ans = 0;
        double half = (h * a * a)/2;
        if (b <= a + 1e-6)
        {
            ans = 90 - atan(b/h)*180/PI;
        }
        else
        {
            x -= half;
            x = half - x;
            b = x/(a*a/2);

            ans =  90 - atan(a/b)*180/PI;
        }
/*
        double tri, rec;
        k = 0;
        bool flag = 1;
        for (i = h/2; i > 1e-6; i /= 2)
        {
            //cout << fixed << "i = " << i << endl;
            while(k+i <= h+1e-6)
            {
                tri = a*a*(k+i)/2;
                rec = a*a*(h-k-i);
                //cout << fixed << "k+i " << k+i << endl;
                //cout << tri << " + " << rec << " = " << tri + rec << endl;
                if (rec + tri < x)break;

                k += i;
            }
            if (abs(k+i-h) < 1e-6 && tri + rec > x)
            {
                flag = 1;
                break;
            }

            //cout << "braked\n\n";
        }
        if (flag)
        {
            double b = x/(h*a/2);
            double ans = 90 - atan(b/h)*180/PI;
            cout << ans << endl;
            return 0;
        }
        double ans = 90 - atan(a/k)*180/PI;
*/
        cout << setprecision(10) << fixed << ans << endl;

        //cout << "Test #" << test_case << ": ";
        //cout << "Case " << test_case << ": ";
    }
    return 0;
}


template< typename T>
T gcd(T a, T b)
{
    if (b == 0)
        return a;
    return gcd(b, a%b);
}
template< typename T>
T modpow(T number, T power, T mod_value)
{
    if (power == 0)
        return 1%mod_value;
    ll u = modpow(number,power/2,mod_value);
    u = (u*u)%mod_value;
    if (power%2 == 1)
        u = (u*number)%mod_value;
    return u;
}


Measured memory_bytes: 256