foo.cc: In function 'void solve()':
foo.cc:133:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<double>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  133 |     for (int i = 0; i + 1 < xs.size(); i ++ )
      |                     ~~~~~~^~~~~~~~~~~
foo.cc:116:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  116 |             scanf("%lf%lf", &tr[i][j].first, &tr[i][j].second);
      |             ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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