Custom compare class

If marks of two student is equal give priority to Roll or Math marks or Biology marks we have to tell it to computer .

include

using namespace std;
class Student{
public:
string name ;
int roll ;
int marks ;
Student(string name , int roll , int marks){
this->name = name ;
this->roll =roll ;
this->marks = marks ;
}
};

class cmp{
public:
bool operator()(Student l , Student r )
{
if(l.marks < r.marks)
return true ;
else
return false ;

}

};
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
priority_queue,cmp> pq;
int n ;
cin >> n ;
for(int i = 0 ; i < n ; i++){
string name ;
int roll , marks ;
cin >> name >> roll >> marks ;
Student obj(name,roll , marks) ;
pq.push(obj) ;
}

while(!pq.empty()){
cout << pq.top().name << " " << pq.top().roll << " " << pq.top().marks() << endl ;

}
return 0 ;

}