C++: Merging two STL vectors using insert function.

vector<int> vec1;
vec1.push_back(5);
vec1.push_back(2);
vec1.push_back(8);
vec1.push_back(4);
vec1.push_back(5);
vector<int> vec2;
vec2.push_back(12);
vec2.push_back(15);
vec2.push_back(20);

vector<int> merge_vec1_vec2=vec1;
merge_vec1_vec2.insert(merge_vec1_vec2.end(),vec2.begin(),vec2.end());
// merge_vec1_vec2 = {5,2,8,4,5,12,15,20}