Compilare: main.c: In function 'main': main.c:128:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("heapuri.in", "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:129:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("heapuri.out", "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:131:5: warning: ignoring return value of 'read', declared with attribute warn_unused_result [-Wunused-result] read(STDIN_FILENO, buf, sizeof buf); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:157:5: warning: ignoring return value of 'write', declared with attribute warn_unused_result [-Wunused-result] write(STDOUT_FILENO, obuf, oblen); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~