Compilare: main.cpp: In function 'void add(int)': main.cpp:20:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | if (j < nr[i].size()) | ~~^~~~~~~~~~~~~~ main.cpp: In function 'void substract(int)': main.cpp:40:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 40 | if (j < nr[i].size()) | ~~^~~~~~~~~~~~~~ In file included from /usr/include/c++/12.2.1/vector:64, from /usr/include/c++/12.2.1/queue:61, from main.cpp:3: In member function 'constexpr std::vector<_Tp, _Alloc>::size_type std::vector<_Tp, _Alloc>::size() const [with _Tp = int; _Alloc = std::allocator<int>]', inlined from 'int main()' at main.cpp:89:30: /usr/include/c++/12.2.1/bits/stl_vector.h:988:40: warning: 'bef' may be used uninitialized [-Wmaybe-uninitialized] 988 | { return size_type(this->_M_impl._M_finish - this->_M_impl._M_start); } | ~~~~~~~~~~~~~~^~~~~~~~~ main.cpp: In function 'int main()': main.cpp:75:17: note: 'bef' was declared here 75 | int it = k, bef; | ^~~