by c cu cub cubi cubic cubic cubi cub cu c of of of o i- i-n- i-n-t- i-n-t-e- i-n-t-e-r- i-n-t-e-r-a- i-n-t-e-r-a-c- i-n-t-e-r-a-c-t- i-n-t-e-r-a-c-t-i- i-n-t-e-r-a-c-t-i-v- i-n-t-e-r-a-c-t-i-v-e i-n-t-e-r-a-c-t-i-v-e i-n-t-e-r-a-c-t-i-v-e i-n-t-e-r-a-c-t-i-v-e