C++ Pair Vector

#include<iostream>
#include<utility>
#include<vector>
#include<iterator>
using namespace std;
int main()
{
    vector<pair<string, int> > a;
    vector<pair<string, int> > :: iterator r;

    a.push_back(make_pair("Aubdur Rob Anik", 73));
    a.push_back(make_pair("Anika Kobir Shock", 104));
    a.push_back(make_pair("Mousumi", 105));

    for(r=a.begin(); r!= a.end(); r++)
    {
        cout << r->first << " --> " << r->second << endl;
    }

    return 0;
}