Compilare: main.cpp: In function 'bool is_prime(int)': main.cpp:31:10: warning: unused variable 'ok' [-Wunused-variable] bool ok = true; ^~ main.cpp: In function 'int main()': main.cpp:45:22: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&n); ^ main.cpp:50:26: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&x); ^