/in/foo.cc: In function 'void dfs(int, int, int)':
/in/foo.cc:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < G[u].size(); i++) {
                     ~~^~~~~~~~~~~~~
/in/foo.cc: In function 'void solve(int, int)':
/in/foo.cc:76:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < G[u].size(); i++) {
                     ~~^~~~~~~~~~~~~
/in/foo.cc:83:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < que[u].size(); i++) {
                     ~~^~~~~~~~~~~~~~~