foo.cc: In function 'int main()':
foo.cc:59:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<node>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   59 |         while(k<a.size()&&a[k].h>b[i].h){
      |               ~^~~~~~~~~

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