#include <iostream>
#include <vector>
#include <string>
#include <time.h>
 
// Gets input from the user's keyboard, returns the input in the form of a double.
double GetNumber( void ) 
{
        std::cout << "Enter Number or 0 to exit: ";
        double ret;
 
        std::cin >> ret;
        return ret;        
}
 
// Retrieves the numbers from the user and stores/returns a vector of doubles.
std::vector<double> GetNumbers( void )
{
        std::vector<double> nums;
        for (;;)
        {
                double num = GetNumber();
                if ( num = 0 )
                        break;
                else
                        nums.push_back( num );
        }
        return nums;        
}
 
int main( void )
{
        std::vector<double> numbers = GetNumbers();
 
        std::cout << "What number from the list do you want to see? ( 1 - " << numbers.size() << ")";
        int choice;
 
        std::cin >> choice;
 
        std::cout << numbers[choice - 1] << std::endl;
 
        return 0;
}