Compilare: main.cpp: In function 'int main()': main.cpp:36:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 36 | for( i = 0; i < s.size(); i++ ) { | ~~^~~~~~~~~~ main.cpp:28:19: warning: variable 'b' set but not used [-Wunused-but-set-variable] 28 | int k, i, j, a, b, c, d; | ^ main.cpp:28:22: warning: variable 'c' set but not used [-Wunused-but-set-variable] 28 | int k, i, j, a, b, c, d; | ^ main.cpp:28:25: warning: variable 'd' set but not used [-Wunused-but-set-variable] 28 | int k, i, j, a, b, c, d; | ^ main.cpp:29:8: warning: variable 'ch' set but not used [-Wunused-but-set-variable] 29 | char ch; | ^~