#include <iostream>
#include <set>
#include <vector>
#include <algorithm>

using namespace std;

    struct Foo {
        int a, b, c;
        Foo(int a, int b, int c) : a(a), b(b), c(c) {}
        bool operator<(const Foo& rhs) const {
            return a < rhs.a;
        }
        friend ostream& operator<<(ostream&, const Foo&);
    };

ostream& operator<<(ostream& stream, const Foo& foo) {
    stream << foo.a << ", " << foo.b << ", " << foo.c;
    return stream;
}

int main() {
    set<Foo> s;
    s.insert({ 1,2,3 });
    s.insert({ 1,3,4 });
    s.insert({ 2,3,1 });
    s.insert({ 2,4,6 });
    s.insert({ 3,5,2 });
    s.insert({ 1,5,7 });

    for (auto x : s) {
        cout << x << endl;
    }

    vector<Foo> v;
    std::copy(s.begin(), s.end(), std::back_inserter(v));
    std::sort (v.begin(), v.end(), [](const Foo& lhs, const Foo& rhs){ return (lhs.b == rhs.b) ? lhs.c > rhs.c : lhs.b > rhs.b; });

    for (auto x : v) {
        cout << x << endl;
    }


    return 0;
}