foo.cc: In function 'int main()':
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=0;i<s.size()-1;i++)
      |                     ~^~~~~~~~~~~
foo.cc:13:45: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   13 |         if(x%11==s[s.size()-1]-'0'||x%11==10&&s[s.size()-1]=='X')
      |                                     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~
foo.cc:17:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   17 |                 for(int i=0;i<s.size()-1;i++)
      |                             ~^~~~~~~~~~~

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