Reuse std::stringstream and std::istream_iterator in loop

I have the following text file:

0 0 0 0 0 1 0 0 2 3 4 2 1 2 1
0 0 0 0 2 7 5 4 5 7 5 4 3
3 2 4 6 2 7 2 7 5 4 5 7 5 4 3
3 2 4 6 2 7 2 7 5 4  5 4 3
0 0 0 0 0 1 0 2 3 4 2 1 2 1
0 0 0 0 0 1 0 0 2 3 4 2 1 2 1
0 0 0 0 2 1 2 1
3 2 4 6 2 7 2 7 5 4 5 7 5 4 3
3 2 4 6 2 0 2 3 4 2 1 2 1
0 0 0 0 0 1 0 0 2 3 4 2 1 2 1
3 2 4 6 2 7 2 7 5 4 5 7 5 4 3

I can read it with the following program:

#include <iostream>
#include <iterator>
#include <fstream>
#include <vector>
#include <string>
#include <sstream>

int main()
{
    std::ifstream is("numbers.txt");
    std::string line;
    std::vector<std::vector<int>> numbers{};
    while (std::getline(is,line)) {
        std::stringstream ss{line};
        std::istream_iterator<int> start{ss},end;
        numbers.emplace_back(start,end);
        std::cout << "Read " << numbers.back().size() << " numbers in row\n";
    }
    std::cout << "Read " << numbers.size() << " rows\n";

    std::cout << "numbers read in:\n";
    for (auto row : numbers) {
        for (auto number : row) {
            std::cout << number << " ";
        }
        std::cout << "\n";
    }
    std::cout << std::endl;
}

I would like to create the std::stringstream and std::istream_iterator only once outside the loop. How could I adjust the iterator to the correct position each time the loop executes in the following program?

#include <iostream>
#include <iterator>
#include <fstream>
#include <vector>
#include <string>
#include <sstream>

int main()
{
    std::ifstream is("numbers.txt");
    std::string line;
    std::vector<std::vector<int>> numbers{};
    std::stringstream ss{line};
    std::istream_iterator<int> start{ss},end;
    while (std::getline(is,line)) {
        ss << line;
        //start = ss.beg;
        numbers.emplace_back(start,end);
        std::cout << "Read " << numbers.back().size() << " numbers in row\n";
    }
    std::cout << "Read " << numbers.size() << " rows\n";

    std::cout << "numbers read in:\n";
    for (auto row : numbers) {
        for (auto number : row) {
            std::cout << number << " ";
        }
        std::cout << "\n";
    }
    std::cout << std::endl;
}