堆栈的头函数使用

#include <iostream>
#include <stack>
using namespace std;
 
int main() {
    stack<int> s;
    s.push(1);
    s.push(2);
    s.push(3);
    cout<<s.top()<<endl;
    cout<<s.size()<<endl;
    s.pop();
    cout<<s.size()<<endl;
    if(s.empty())
        cout<<"Empty"<<endl;
    else
        cout<<"Not Empty"<<endl;
    return 0;
}