#include <iostream>
#include <clocale>
#include <string>

using namespace std;
string dvoiczn (unsigned long long x);
unsigned long long obratno(string str);

int main()
{
    setlocale(LC_ALL, "ru");
    unsigned long long  n;
    string stroka1, stroka2, stroka3;
    cout << "Введите  n ";
    cin >> n;
    unsigned long long int j = 0, i = 1;
    while ( j < n)
    {
        stroka1 = dvoiczn(i);
        stroka2 = dvoiczn(obratno(stroka1));
        stroka3 = stroka2.substr(stroka2.size() - stroka1.size());
        if (stroka3 == stroka1)
            j++;
        i++;


    }
            cout << stroka1<< endl;



    return 0;
}
string dvoiczn(unsigned long long x)
{
    string itog;
    do
    {
    itog = char(int('0') + (x % 2))+itog;
    x /= 2;
    } while (x > 0);
    return itog;
}
unsigned long long obratno(string str)
{
    if (str.size() == 1)
        return str[0] - '0';
    int i = str.size() - 1;
    return obratno(str.substr(0, i))*10 + (str[i]-unsigned long long('0'));
}