/in/foo.cc: In function 'int get(int, int)':
/in/foo.cc:38:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < graph_r[node].size(); i++) {
                     ~~^~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int work()':
/in/foo.cc:85:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < graph[elem].size(); i++) {
                         ~~^~~~~~~~~~~~~~~~~~~~