/in/foo.cc: In function 'int main()':
/in/foo.cc:25:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(pos=0;pos<input.size();){
               ~~~^~~~~~~~~~~~~
/in/foo.cc:45:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if(pos<input.size()){
        ~~~^~~~~~~~~~~~~
/in/foo.cc:48:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       for(;pos<input.size();){
            ~~~^~~~~~~~~~~~~
/in/foo.cc:67:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      }while(pos<input.size());
             ~~~^~~~~~~~~~~~~