#include <iostream>
#include <set>
using namespace std;

struct Pair
{
    int first;
    int second;
    bool operator< (const Pair &rhs) const //重载<用于set中比较
    {
        if(this->first != rhs.first) return this->first < rhs.first;
        else return this->second < rhs.second;
    }
    friend ostream& operator<< (ostream &os, const Pair &p);//重载输出，方便遍历然后输出
};//自定义一个二元组类型

ostream& operator<< (ostream &os, const Pair &p)
{
    os<<"("<<p.first<<","<<p.second<<")";
    return os;
}
int sd[40];
int n;

set<Pair> s;

int main()
{
    cin>>n;
    for(int i = 0; i < n; i ++)
    {
        cin>>sd[i];
    }
    ...