foo.cc: In function 'int main()':
foo.cc:17:15: warning: comparison of integer expressions of different signedness: 'std::stack<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   17 |    if(s.size()>max)
      |       ~~~~~~~~^~~~
foo.cc:11:6: warning: unused variable 'cnt' [-Wunused-variable]
   11 |  int cnt=0;
      |      ^~~

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