Main.c: In function 'compare':
Main.c:20:21: error: 'm' undeclared (first use in this function)
   20 |     for (i = 0; i < m; i++) {
      |                     ^
Main.c:20:21: note: each undeclared identifier is reported only once for each function it appears in
Main.c: In function 'main':
Main.c:45:5: warning: implicit declaration of function 'qsort' [-Wimplicit-function-declaration]
   45 |     qsort(students, n, sizeof(Student), compare);
      |     ^~~~~