#include<bits/stdc++.h>
using namespace std;
int main()
 {
     int a[] = {1,2,3};
     set<int> s(a,a+3);
     set<int>::iterator iter;
     if((iter = s.find(2)) != s.end())
    {
        cout<<*iter<<endl;//Êä³öΪ2
    }
     return 0;
 }