foo.cc: In function 'int countChar(std::string, char)':
foo.cc:6:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    6 |  for(int i=0;i<s1.size();i++)
      |              ~^~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:17:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   17 |  for(int i=0;i<s.size();i++)
      |              ~^~~~~~~~~
foo.cc:23:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   23 |   while(rk<s.size()&&countChar(a,s[rk]))
      |         ~~^~~~~~~~~
foo.cc:15:6: warning: unused variable 'maxn' [-Wunused-variable]
   15 |  int maxn=0,t=0,Max=0,rk=0;
      |      ^~~~
foo.cc:15:13: warning: unused variable 't' [-Wunused-variable]
   15 |  int maxn=0,t=0,Max=0,rk=0;
      |             ^

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