/in/foo.cc: In function 'bool init()':
/in/foo.cc:59:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<n;i++)
               ~^~
/in/foo.cc:61:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<n;i++)
               ~^~
/in/foo.cc:62:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int j=0;j<n;j++)
               ~^~
/in/foo.cc:66:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<n;i++)
               ~^~
/in/foo.cc:80:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<n;i++)
               ~^~
/in/foo.cc:81:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int j=i+1;j<n;j++)
                 ~^~
/in/foo.cc:86:59: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   graph[i][j] = graph[j][i] = dx * dx + dy * dy + dz * dz <= r * r * 4;
                               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
/in/foo.cc: In function 'bool bfs()':
/in/foo.cc:96:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i=0;i<n;i++)
                ~^~