vec

#include <iostream>
#include <vector>

int main()
{
    double temp, n = 3;
    std::vector<std::vector<double>> a;
    std::vector<double> b;
    setlocale(LC_ALL, "Rus");

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            std::cin >> temp;
            b.push_back(temp);
        }
        a.push_back(b);
        b.clear();
    }

    for (int i = 0; i < 5; i++) {
        for (int j = 0; j < n; j++) {
            std::cout << a[i][j] << " ";
        }
        std::cout << std::endl;
    }
    return 0;
}