foo.cc: In function 'int main()':
foo.cc:24:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |   for(int j=0; j<e[i].size(); j++) {
      |                ~^~~~~~~~~~~~

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