#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

int main()
{
    int a = 19, b = 19, c = 37, d = 46;
    int all = 0, succ = 0;

    srand(time(NULL));

    for(int i = 0; i < 1000000000; ++i)
    {
        //Pasirenka urna
        if(rand() % 2 == 0)
        {
            // Traukia pirma
            if(rand() % (a + b)  < a)
            {
                //Jei istraukia balta, traukia antra
                if(rand() % (a + b - 1) < a - 1)
                {
                    //Istrauke ir antra balta
                    ++succ;
                }

                ++all;
            }
        }
        else
        {
            // Traukia pirma
            if(rand() % (c + d) < c)
            {
                //Jei istraukia balta, traukia antra
                if(rand() % (c + d - 1) < c - 1)
                {
                    //Istrauke ir antra balta
                    ++succ;
                }

                ++all;
            }
        }
    }

    cout << (double)succ / all << endl;

    return 0;
}