#include<iostream>
#include<vector>
#include<queue>
#include<stack>
#include<cmath>
#include<map>
using namespace std;
queue<int>q;
stack<int>s;
vector<int>v;
int main(){
	int x;
	for(int i=1;i<=10;i++){
		cin>>x;
		v.push_back(x);
	}
	cout<<v.size()<<endl;
	while(v.empty())
		v.pop_back();
	cout<<v[0]<<" "<<v[1]<<" "<<v.size();
	return 0;
}

为什么pop_back 删完后还是十个元素，数也没有删除