#include <bits/stdc++.h>
#include <ext/rope>
using namespace std;
using namespace __gnu_cxx;
typedef long long ll;
const ll MAXN = 1e5 + 100;
#define x first
#define y second
int main() {
    double m, y, x, n;
    cin >> m >> n >> x;
    if (m * m + n * n <= 1)
        y = cos(m) * cos(m) + 3 * n * x;
    else
        y = log(2 * n + m * m);
    cout << y;

}