foo.cc: In function 'void dfs2(int)':
foo.cc:12:20: warning: comparison of integer expressions of different signedness: 'std::stack<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   12 |         if(l.size()==n)
      |            ~~~~~~~~^~~
foo.cc:14:39: warning: unused variable 'f' [-Wunused-variable]
   14 |                 stack<int> o;int st=0,f=0,lf=0;
      |                                       ^
foo.cc:14:43: warning: unused variable 'lf' [-Wunused-variable]
   14 |                 stack<int> o;int st=0,f=0,lf=0;
      |                                           ^~
foo.cc: In function 'void dfs(int)':
foo.cc:42:20: warning: comparison of integer expressions of different signedness: 'std::stack<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   42 |         if(l.size()==n)
      |            ~~~~~~~~^~~

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