/in/foo.cc: In function 'void dijkstra()':
/in/foo.cc:49:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < edges[u].size(); i += 1){
                         ~~^~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'void dfs(int, int, int)':
/in/foo.cc:71:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < edges[u].size(); i += 1)
                     ~~^~~~~~~~~~~~~~~~~