Compilare: main.cpp: In function 'int main()': main.cpp:52:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 52 | for (int i = 0; i < nr.size(); i++) { | ~~^~~~~~~~~~~ main.cpp:60:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 60 | for (int i = p + 1; i < nr.size(); i++) { | ~~^~~~~~~~~~~ main.cpp:68:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 68 | for (int i = 0; i < nr.size(); i++) { | ~~^~~~~~~~~~~ main.cpp:76:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 76 | for (int i = p + 1; i < nr.size(); i++) { | ~~^~~~~~~~~~~ main.cpp:48:14: warning: unused variable 'ch' [-Wunused-variable] 48 | char ch; | ^~