how to append to a vector c++

vector<int> a;
vector<int> b;
// Appending the integers of b to the end of a 
a.insert(a.end(), b.begin(), b.end());

//vector.push_back is the function. For example, if we want to add
//3 to a vector, it is just vector.push_back(3)
vector <int> vi;
vi.push_back(1); //[1]
vi.push_back(2); //[1,2]

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