Compilare: main.cpp: In function 'int main()': main.cpp:20:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | while (i < input.length()) { | ~~^~~~~~~~~~~~~~~~ main.cpp:33:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 33 | while (i < input.length() && (input[i] == ')' || input[i] == ' ')) { | ~~^~~~~~~~~~~~~~~~ main.cpp:37:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 37 | if (i < input.length() && input[i] >= '0' && input[i] <= '9') { | ~~^~~~~~~~~~~~~~~~ main.cpp:39:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 39 | while (i < input.length() && input[i] >= '0' && input[i] <= '9') { | ~~^~~~~~~~~~~~~~~~ main.cpp:50:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 50 | while (i < input.length() && input[i] >= 'a' && input[i] <= 'z') { | ~~^~~~~~~~~~~~~~~~ main.cpp:57:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 57 | while (i < input.length() && input[i] >= '0' && input[i] <= '9') { | ~~^~~~~~~~~~~~~~~~