Compilare: user.cpp: In member function ‘bool Hash::isIn(long int, long int)’: user.cpp:23:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<C[dir].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:40:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("twosets.in","r",stdin); ^ user.cpp:41:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("twosets.out","w",stdout); ^ user.cpp:43:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld\n",&t); ^ user.cpp:47:41: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] memset(s,0,sizeof(s)); gets(s+1); n=0; ^ user.cpp:63:41: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] memset(s,0,sizeof(s)); gets(s+1); n=0; good=true; ^ /tmp/cc3b2jNw.o: In function `main': user.cpp:(.text.startup+0xbf): warning: the `gets' function is dangerous and should not be used.