C++ | pair

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

int main()
{
typedef pair<int, int> pii;
typedef pair<string, pii> psii;
vector<psii> grades;
grades.push_back(make_pair("a", make_pair(1, 2)));
grades.push_back(make_pair("a", make_pair(2, 1)));
grades.push_back(make_pair("a", make_pair(1, 3)));
grades.push_back(make_pair("b", make_pair(2, 1)));
grades.push_back(make_pair("b", make_pair(1, 1)));
grades.push_back(make_pair("c", make_pair(1, 1)));

sort(grades.begin(), grades.end());
vector<psii>::iterator iter, iend = grades.end();
for(iter = grades.begin(); iter != iend; ++iter) {
cout << iter->first << ' ' << iter->second.first << ' ' << iter->second.second << endl;
}

return 0;
}