Compilare: user.cpp:13:10: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main(void) ^ user.cpp: In function ‘int main()’: user.cpp:19:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0; k<s.length(); k++) sm+=(s[k]-48); ^ user.cpp:20:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=1; j<=s.length(); j++)if(9*j>sm){cout<<9*j-sm<<'\n'; break;} ^