错在哪了呜呜呜呜

#include<bits/stdc++.h>
using namespace std;
struct birthday
{
	string name;
	int year;
	int month;
	int day;
};
int main()
{
	int n;
    cin>>n;
    birthday a[n];
    for(int i=1;i<=n;i++)
    {
    	cin>>a[i].name >>a[i].year >>a[i].month >>a[i].day ;
	}
    for(int i=1;i<=n;i++)
    {
    	for(int j=i+1;j<=n;j++)
    	{
    		if(a[i].year <a[j].year || a[i].year ==a[j].year && a[i].month <a[j].month ||a[i].month == a[j].month &&a[i].day <a[j].day )
			{
    			swap(a[i],a[j]);
			} 
		}
		
	}
	for(int i=1;i<=n;i++)
	{
		cout<<a[i].name <<" ";
		cout<<a[i].year <<" "<<a[i].month <<" "<<a[i].day ;
	}
	return 0;
 }