#include <stdio.h>
#include <stdlib.h>

typedef struct{
    int id;
    char name[100];
    int a, b, c;
    double average;
} Student;

void calc(Student* st){
    double sum = st->a + st->b + st->c;
    sum /= 3;
    st->average = sum;
}
int cmp(const void* a, const void* b){
    return ((Student*)a)->average - ((Student*)b)->average;
}

int main(){
    Student st[] = {
        {1, "Chang", 10, 9, 8},
        {2, "Wan", 1, 2, 4},
        {3, "Liu", 2, 3, 5}
    };
    for(int i = 0; i < 3; i++){
        calc(&st[i]);
    }

    qsort(st, 3, sizeof(Student), cmp);
    for(int i = 0; i < 3; ++i){
        printf("Name: %s, Average: %.6lf\n", st[i].name, st[i].average);
    }
    return 0;
}