/in/foo.cc: In function 'int main()':
/in/foo.cc:14:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(i=0;i<num.size()-1;++i)
         ~^~~~~~~~~~~~~
/in/foo.cc:31:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for (i=0;i<num.size()-n;++i)
          ~^~~~~~~~~~~~~
/in/foo.cc:12:11: warning: unused variable 't' [-Wunused-variable]
 int n,i,k,t,c;
           ^
/in/foo.cc:12:13: warning: unused variable 'c' [-Wunused-variable]
 int n,i,k,t,c;
             ^