Compilare: main.cpp: In function 'void calcPi(std::string&)': main.cpp:13:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 13 | for(int i=2;i<=s.size();++i){ | ~^~~~~~~~~~ main.cpp: In function 'void solve(std::string&, std::string&)': main.cpp:28:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 28 | for(int i = 1; i <= b.size(); i++) { | ~~^~~~~~~~~~~ main.cpp:35:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 35 | if(k == a.size()) { | ~~^~~~~~~~~~~