Eroare de compilare: user.cpp: In function ‘int main(int, const char**)’: user.cpp:25:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.length() && ok == 1; i ++ ) { ^ user.cpp:41:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.length() && ok == 1; i ++ ) { ^ /tmp/ccHOSPVy.o: In function `std::tr1::_Hashtable<std::pair<int, int>, std::pair<int, int>, std::allocator<std::pair<int, int> >, std::_Identity<std::pair<int, int> >, std::equal_to<std::pair<int, int> >, std::tr1::hash<std::pair<int, int> >, std::tr1::__detail::_Mod_range_hashing, std::tr1::__detail::_Default_ranged_hash, std::tr1::__detail::_Prime_rehash_policy, false, true, true>::_M_rehash(unsigned int)': user.cpp:(.text._ZNSt3tr110_HashtableISt4pairIiiES2_SaIS2_ESt9_IdentityIS2_ESt8equal_toIS2_ENS_4hashIS2_EENS_8__detail18_Mod_range_hashingENSA_20_Default_ranged_hashENSA_20_Prime_rehash_policyELb0ELb1ELb1EE9_M_rehashEj[_ZNSt3tr110_HashtableISt4pairIiiES2_SaIS2_ESt9_IdentityIS2_ESt8equal_toIS2_ENS_4hashIS2_EENS_8__detail18_Mod_range_hashingENSA_20_Default_ranged_hashENSA_20_Prime_rehash_policyELb0ELb1ELb1EE9_M_rehashEj]+0x5d): undefined reference to `std::tr1::hash<std::pair<int, int> >::operator()(std::pair<int, int>) const' /tmp/ccHOSPVy.o: In function `main': user.cpp:(.text.startup+0x1dd): undefined reference to `std::tr1::hash<std::pair<int, int> >::operator()(std::pair<int, int>) const' user.cpp:(.text.startup+0x320): undefined reference to `std::tr1::hash<std::pair<int, int> >::operator()(std::pair<int, int>) const' collect2: error: ld returned 1 exit status