就是80分，求大佬帮忙改改~

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;

struct Student
{
    string name;
    int year;
    int month;
    int day;
    int num;
};

bool compare(const Student &s1, const Student &s2)
{
    return s1.num < s2.num;
}

int main()
{
    int n;
    cin>>n;
    vector<Student> students(n);
    for(int i=0;i<n;i++)
    {
        cin>>students[i].name >> students[i].year >> students[i].month >> students[i].day;
        students[i].num = students[i].year * 10000 + students[i].month * 100 + students[i].day;
    }
    sort(students.begin(),students.end(), compare);
    for(int i=0;i<n;i++)
    {
        cout<<students[i].name<<endl;
    }
    return 0;
}

我真的不知道怎么办了……