Compilare: user.cpp: In function ‘bool check(int)’: user.cpp:106:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (arb[*it].size() < K) ^ user.cpp: In function ‘int get_number()’: user.cpp:136:46: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(Buffer , 1 , Bsize , stdin); ^ user.cpp:147:46: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(Buffer , 1 , Bsize , stdin); ^ user.cpp: In function ‘int main()’: user.cpp:157:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mess.in","r",stdin); ^ user.cpp:158:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mess.out","w",stdout); ^ user.cpp:160:38: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(Buffer , 1 , Bsize , stdin); p = 0; ^