/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:10:6: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(t==tar.length()) {
     ~^~~~~~~~~~~~~~
/in/foo.cc:15:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;t+i<=tar.length();i++){
              ~~~^~~~~~~~~~~~~~