Compilare: user.cpp: In function ‘int phi(int)’: user.cpp:7:12: warning: unused variable ‘cn’ [-Wunused-variable] i64 i, cn = n, ans = n; ^ user.cpp: In function ‘int main()’: user.cpp:42:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("inversmodular.in","r",stdin); ^ user.cpp:43:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("inversmodular.out","w",stdout); ^ user.cpp:45:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&k,&n); ^