Compilare: main.cpp: In function 'int main()': main.cpp:32:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 32 | for(int i = 0;i < a.size(); ++i) dq.push_back(b[i]),dq2.push_back(a[i]); | ~~^~~~~~~~~~ main.cpp:34:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 34 | for(int i = a.size();i < b.size(); ++i) | ~~^~~~~~~~~~