abc184_d - Increment Of Coins

using namespace std;
int const NMAX = 100 + 1;
double dp[NMAX][NMAX][NMAX];
int main(void)
{
    ios::sync_with_stdio(false), cin.tie(NULL);
    int a, b, c;
    cin >> a >> b >> c;
    for (int x = 99; x >= 0; --x)
    {
        for (int y = 99; y >= 0; --y)
        {
            for (int z = 99; z >= 0; --z)
            {
                double d = x + y + z;
                dp[x][y][z] = x / d * (dp[x + 1][y][z] + 1) +
                              y / d * (dp[x][y + 1][z] + 1) +
                              z / d * (dp[x][y][z + 1] + 1);
            }
        }
    }
    cout << setprecision(12) << fixed << dp[a][b][c] << endl;
    return 0;
}