/in/foo.cc: In function 'int main()':
/in/foo.cc:8:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |         while(i<s.size()){
      |               ~^~~~~~~~~
/in/foo.cc:12:40: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |                 }while(isdigit(s[i])&&i<s.size()){
      |                                       ~^~~~~~~~~
/in/foo.cc:16:22: warning: 'a' may be used uninitialized [-Wmaybe-uninitialized]
   16 |                 else if(a=='-')ans-=x;
      |                      ^~
/in/foo.cc:5:14: note: 'a' was declared here
    5 |         char a;
      |              ^