/in/foo.cc: In function 'int main()':
/in/foo.cc:16:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<str.length()-7;j++) {
               ~^~~~~~~~~~~~~~~
/in/foo.cc:20:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<str.length()-2;j++) {
               ~^~~~~~~~~~~~~~~
/in/foo.cc:27:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<str.length();j++) {
               ~^~~~~~~~~~~~~
/in/foo.cc:31:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<str.length()-1;j++) {
               ~^~~~~~~~~~~~~~~