bdfz_2024_summer/test.cpp

#include<bits/stdc++.h>
using namespace std;

int main(){
    set<int>s;
    s.insert(2);
    s.insert(3);
    auto it = s.lower_bound(2);
    cout<<(*(--it))<<endl;
    cout<<(*(++it))<<endl;
    cout<<(*(--it))<<endl;
    cout<<(*(--it))<<endl;
}