Compilare: user.c: In function ‘main’: user.c:40:5: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("padure.in", "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ user.c:41:5: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("padure.out", "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ user.c:43:5: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result] read(STDIN_FILENO, buf, CHUNK); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~