Compilare: user.cpp: In function 'int hash_it(unsigned int)': user.cpp:24: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'long long int doit(int)': user.cpp:40: warning: unused variable 'can' user.cpp: In function 'int main()': user.cpp:76: warning: unused variable 'key' /tmp/ccUUwX9m.o: In function `main': user.cpp:(.text+0x22b): warning: the `gets' function is dangerous and should not be used.