Sort structures by marks, then by name, in C Solution, output & explanation

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

struct student {
    const char *name;
    int marks;
};

static int cmp(const void *a, const void *b) {
    const struct student *x = a, *y = b;
    if (x->marks != y->marks)
        return (y->marks > x->marks) - (y->marks < x->marks);   /* higher marks first */
    return strcmp(x->name, y->name);                            /* then A to Z */
}

int main(void) {
    struct student s[] = {{"Ravi", 82}, {"Asha", 91}, {"Meera", 82}, {"John", 75}, {"Dev", 91}};
    qsort(s, 5, sizeof s[0], cmp);
    for (int i = 0; i < 5; i++)
        printf("%-6s %d\n", s[i].name, s[i].marks);
    return 0;
}

Asha   91
Dev    91
Meera  82
Ravi   82
John   75