Compilare: user.cpp: In function ‘void first_question()’: user.cpp:51:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[x].size(); ++i) ^ user.cpp: In function ‘void another_question()’: user.cpp:99:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < coridoare.size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:118:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < coridor.size(); ++j) { ^ user.cpp: In function ‘bool cmp_(const cor_&, const cor_&)’: user.cpp:26:1: warning: control reaches end of non-void function [-Wreturn-type] } ^