/in/foo.cc: In function 'std::vector<int> MergeSubs(const std::vector<int>&)':
/in/foo.cc:11:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < arr.size(); i++) {
                     ~~^~~~~~~~~~~~
/in/foo.cc:14:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if (i == arr.size() - 1 || arr[i] >= arr[i + 1]) {
             ~~^~~~~~~~~~~~~~~~~
/in/foo.cc:25:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < subs.size() - 1; i++) {
                         ~~^~~~~~~~~~~~~~~~~
/in/foo.cc:32:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < subs.size(); i++) {
                         ~~^~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:60:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < result1.size(); i++) {
                     ~~^~~~~~~~~~~~~~~~
/in/foo.cc:64:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < result2.size(); i++) {
                     ~~^~~~~~~~~~~~~~~~