求助

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
using namespace std;
struct B {
    string name;
    int ye;
    int mon;
    int d;
};
bool compare(const B& a, const B& b) {
    if (a.ye != b.ye) return a.ye < b.ye; 
    if (a.mon != b.mon) return a.mon < b.mon; 
    return a.d < b.d; 
}
int main() {
    int n;
    cin >> n;
    vector<B> bi(n);
    for (int i = 0; i < n; ++i) {
        cin >> bi[i].name >> bi[i].ye >> bi[i].mon >> bi[i].d;
    }
    sort(bi.begin(), bi.end(), compare);
    for (const auto& b : bi) {
        cout << b.name << endl;
    }
    return 0;
}