/in/foo.cc: In function 'int main()':
/in/foo.cc:46:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int j = 0; j < ans.size(); j++) {
                    ~~^~~~~~~~~~~~
/in/foo.cc:58:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int j = 0; j < ans.size(); j++) {
                    ~~^~~~~~~~~~~~
/in/foo.cc:66:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < ans.size(); i++) {
                  ~~^~~~~~~~~~~~
/in/foo.cc:74:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < va.size(); i++) {
                  ~~^~~~~~~~~~~
/in/foo.cc:75:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < vb.size(); j++) {
                   ~~^~~~~~~~~~~
/in/foo.cc:82:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int z = 0; z < res.size(); z++) {
                     ~~^~~~~~~~~~~~
/in/foo.cc:91:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < res.size(); i++) {
                  ~~^~~~~~~~~~~~