Compilare: user.c: In function ‘main’: user.c:21:5: warning: implicit declaration of function ‘log2’ [-Wimplicit-function-declaration] int b=log2(e); ^ user.c:21:11: warning: incompatible implicit declaration of built-in function ‘log2’ [enabled by default] int b=log2(e); ^ user.c:42:5: warning: passing argument 1 of ‘free’ makes pointer from integer without a cast [enabled by default] free(v); ^ In file included from user.c:1:0: /usr/include/stdlib.h:488:13: note: expected ‘void *’ but argument is of type ‘int’ extern void free (void *__ptr) __THROW; ^ user.c:11:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fp,"%d %d", &n,&m); ^ user.c:17:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fp, "%d %d", &r[0],&r[1]); ^ user.c:18:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fp, "%d %d %d", &c,&d,&e); ^ user.c:27:15: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fp, "%d", &v); ^