Compilare: main.cpp: In function 'void c1()': main.cpp:27:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 27 | for (int i = k; i < s.size(); ++i) | ~~^~~~~~~~~~ main.cpp: In function 'void c2()': main.cpp:35:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 35 | for (int i = 1; i < s.size(); ++i) { | ~~^~~~~~~~~~