/in/foo.cc: In function 'int main()':
/in/foo.cc:24:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 1; i < v.size(); ++i)
                  ~~^~~~~~~~~~
/in/foo.cc:28:18: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
    if (int(v[i]) == v[i] ^ int(v[i - 1]) == v[i - 1])
                   
/in/foo.cc:35:13: warning: 'j' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if (int(v[j]) == v[j])
             ^