foo.cc: In function 'int Cout(std::string, char)':
foo.cc:5:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    5 |  for(int i=0;i<s.size();i++){
      |              ~^~~~~~~~~
foo.cc: In function 'int f(std::string)':
foo.cc:11:6: warning: unused variable 't' [-Wunused-variable]
   11 |  int t,i,n,len,rk;
      |      ^
foo.cc:11:8: warning: unused variable 'i' [-Wunused-variable]
   11 |  int t,i,n,len,rk;
      |        ^

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