map, set, iterator

#include <bits/stdc++.h>

using namespace std;

int main() {
    set < pair <int, int> > st;
    set < pair <int, int> > :: iterator set_it;
    st.insert({1, 0});
    st.insert({3, 0});
    set_it = st.begin();
    cout << set_it->first << endl;
    map <int, int> mp;
    map <int, int> :: iterator it;

    mp[2] = 5;
    mp[7] = 10;
    mp[9] = 7;

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