Compilare: user.c: In function ‘main’: user.c:12:10: warning: operation on ‘a’ may be undefined [-Wsequence-point] x=(++a)*(a+1)*(a+2); ~^~~~ user.c:12:10: warning: operation on ‘a’ may be undefined [-Wsequence-point] user.c:8:5: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%lld", &s); ^~~~~~~~~~~~~~~~~~~~~~~