/in/foo.cc: In function 'int main()':
/in/foo.cc:8:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s2.size();i++)
               ^
/in/foo.cc:9:8: warning: unused variable 'c' [-Wunused-variable]
  {char c;int num;
        ^