foo.cc: In function 'int main()':
foo.cc:15:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |         while(i<s.size())
      |               ~^~~~~~~~~
foo.cc:17:25: warning: variable 'f' set but not used [-Wunused-but-set-variable]
   17 |                 int j=i,f=1,k=i;
      |                         ^

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