/in/foo.cc: In function 'int main()':
/in/foo.cc:15:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if(s.size()==c){
        ~~~~~~~~^~~
/in/foo.cc:21:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int k=i+1;k<=n && k<i+c-s.size();k++)
                           ~^~~~~~~~~~~~~
/in/foo.cc:13:12: warning: unused variable 'sz' [-Wunused-variable]
  int i=1,j,sz;
            ^~