Compilare: main.cpp: In function 'void rebuild(int, int, int, int)': main.cpp:28:36: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 28 | if (x1 <= x2 && y1 <= y2 && i < s.size()) | ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:75:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 75 | for (i = 0; i < s.size(); i++) | ~~^~~~~~~~~~