Compilare: user.c: In function ‘main’: user.c:19:7: warning: variable ‘_ret’ set but not used [-Wunused-but-set-variable] int _ret; ^ user.c: In function ‘solve’: user.c:152:16: warning: unused variable ‘idx_a0_in_b’ [-Wunused-variable] int free_idx,idx_a0_in_b; ^ user.c:151:11: warning: unused variable ‘x’ [-Wunused-variable] int j,k,x; ^ user.c:150:8: warning: unused variable ‘similar’ [-Wunused-variable] char similar; ^ user.c: In function ‘main’: user.c:34:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d",a+i); ^ user.c:44:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d",&_b); ^ user.c: In function ‘check_similarity’: user.c:142:6: warning: ‘similar’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (!similar) return i; ^