prepare (1/3): 
finished

make (2/3): 
cc -c main.c
main.c: In function 'main':
main.c:73:39: warning: passing argument 4 of 'qsort' from incompatible pointer type [-Wincompatible-pointer-types]
     qsort(es, m, sizeof(struct Edge), cp_w);
                                       ^~~~
In file included from main.c:1:0:
/usr/include/stdlib.h:827:13: note: expected '__compar_fn_t {aka int (*)(const void *, const void *)}' but argument is of type 'int (*)(void *, void *)'
 extern void qsort (void *__base, size_t __nmemb, size_t __size,
             ^~~~~
main.c:82:39: warning: passing argument 4 of 'qsort' from incompatible pointer type [-Wincompatible-pointer-types]
     qsort(es, m, sizeof(struct Edge), cp_u);
                                       ^~~~
In file included from main.c:1:0:
/usr/include/stdlib.h:827:13: note: expected '__compar_fn_t {aka int (*)(const void *, const void *)}' but argument is of type 'int (*)(void *, void *)'
 extern void qsort (void *__base, size_t __nmemb, size_t __size,
             ^~~~~
cc -o main main.o
finished

clean (3/3): 
finished

all task finished, build successfully