/in/foo.cc: In function 'int main()':
/in/foo.cc:7:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    7 |         for(int i=1;i<=s.size();i++)
      |                     ~^~~~~~~~~~
/in/foo.cc:10:29: warning: value computed is not used [-Wunused-value]
   10 |                         s[i]=='6';
/in/foo.cc:12:29: warning: value computed is not used [-Wunused-value]
   12 |                         s[i]=='9';
/in/foo.cc:16:29: warning: value computed is not used [-Wunused-value]
   16 |                         s[i]==0;