foo.cc: In function ‘int main()’:
foo.cc:18:39: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
   18 |     if(ans%11==(s[12]-'0')||s[12]=='X'&&ans%11==10){
foo.cc:23:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   23 |         for(int i=0;i<s.size()-1;i++) cout<<s[i];
      |                     ~^~~~~~~~~~~
foo.cc:8:20: warning: unused variable ‘j’ [-Wunused-variable]
    8 |     register int i,j; //寄存器变量加速
      |                    ^