Compilare: user.cpp: In function ‘int count_fractions(int)’: user.cpp:25:19: warning: suggest parentheses around comparison in operand of ‘&’ [-Wparentheses] if((x*j)&n==0) ^ user.cpp: In function ‘int main()’: user.cpp:40:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("farey.in","r",stdin); ^ user.cpp:41:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("farey.out","w",stdout); ^ user.cpp:42:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&n,&k); ^