/in/foo.cc: In function 'void solve()':
/in/foo.cc:32:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < v.size(); ++i)
                  ~~^~~~~~~~~~
/in/foo.cc:34:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < v.size() - 1; ++i) {
                  ~~^~~~~~~~~~~~~~