foo.cc: In function 'int main()':
foo.cc:4:9: error: 'cin' was not declared in this scope
    4 |         cin>>l>>m;
      |         ^~~
foo.cc:1:1: note: 'std::cin' is defined in header '<iostream>'; did you forget to '#include <iostream>'?
  +++ |+#include <iostream>
    1 | using namespace std;
foo.cc:24:9: error: 'cout' was not declared in this scope
   24 |         cout<<tree;
      |         ^~~~
foo.cc:24:9: note: 'std::cout' is defined in header '<iostream>'; did you forget to '#include <iostream>'?

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