/in/foo.cc: In function 'void getnxt()':
/in/foo.cc:7:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i<s2.size();i++){
              ~^~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:18:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s1.size();i++){
              ~^~~~~~~~~~
/in/foo.cc:22:7: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(j==s2.size()){
      ~^~~~~~~~~~~