70分求助

代码如下：

#include <iostream>
using namespace std;
int n = 0;
struct Students{
    int chinese = 0;
    int maths = 0;
    int english = 0;
    int all;
    int id = 0;
};
int main(){
    cin>>n;
    Students stu[n];
    for(int i = 0;i < n;i++){
        stu[i].id = i + 1;
        cin>>stu[i].chinese>>stu[i].maths>>stu[i].english;
        stu[i].all = stu[i].chinese+stu[i].english+stu[i].maths;
    }
    for(int i = 0;i < n;i++){
        for(int j = 0,m = 0;j < i;j++){
            if(stu[j].all < stu[i].all){
                m = stu[i].all;
                stu[i].all = stu[j].all;
                stu[j].all = m;
                m = stu[i].id;
                stu[i].id = stu[j].id;
                stu[j].id = m;
            }
        }
    }
    for(int i = 0;i < 5;i++){
        cout<<stu[i].id<<" "<<stu[i].all<<endl;
    }
    return 0;
}