/in/foo.cc: In function 'int main()':
/in/foo.cc:6:11: warning: unused variable 'k' [-Wunused-variable]
  {int i,j,k,l,o,p,lena,lenb;
           ^
/in/foo.cc:6:13: warning: unused variable 'l' [-Wunused-variable]
  {int i,j,k,l,o,p,lena,lenb;
             ^
/in/foo.cc:6:15: warning: unused variable 'o' [-Wunused-variable]
  {int i,j,k,l,o,p,lena,lenb;
               ^
/in/foo.cc:6:17: warning: unused variable 'p' [-Wunused-variable]
  {int i,j,k,l,o,p,lena,lenb;
                 ^