Compilare: main.cpp: In function 'long long unsigned int euler(int)': main.cpp:15:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=3; i*i<=n; i+=2) ~~~^~~ main.cpp:6:26: warning: unused variable 'a' [-Wunused-variable] unsigned long long p,a,copie,i; ^ main.cpp:6:28: warning: variable 'copie' set but not used [-Wunused-but-set-variable] unsigned long long p,a,copie,i; ^~~~~ main.cpp: In function 'int main()': main.cpp:34:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("fractii.in","r",stdin); ^ main.cpp:35:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("fractii.out","w",stdout); ^ main.cpp:38:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%llu",&n); ^