how to add an element in a vector of vector code example

Example: Appending a vector to a vector in C++

Input:
    vector<int> v1{ 10, 20, 30, 40, 50 };
    vector<int> v2{ 100, 200, 300, 400 };

    //appending elements of vector v2 to vector v1
    v1.insert(v1.end(), v2.begin(), v2.end());

    Output:
    v1: 10 20 30 40 50 100 200 300 400
    v2: 100 200 300 400