Compilare: main.cpp: In function 'void add(std::string&, int)': main.cpp:18:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 18 | for(i = 0;i < s.size();i++){ | ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:39:15: warning: unused variable 'nr' [-Wunused-variable] 39 | int n,i,m,nr,nr2,k,a,j,ans = 0,b,c; | ^~ main.cpp:39:18: warning: unused variable 'nr2' [-Wunused-variable] 39 | int n,i,m,nr,nr2,k,a,j,ans = 0,b,c; | ^~~