foo.cc: In function 'int main()':
foo.cc:12:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |         for(int i=0;i<s.size() ;i++)
      |                     ~^~~~~~~~~
foo.cc:17:17: warning: unused variable 'c1' [-Wunused-variable]
   17 |             int c1=c,f=0;
      |                 ^~

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