In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

Ex Input:
Lightning can travel _ miles or more horizontally from the storm, then strike the ground.

Ex Output:
six

Ex Input:
Cigarette smokers have up to a _ times higher incidence of bladder cancer than non-smokers.

Ex Output:
four

Ex Input:
Echocardiography demonstrates in clear, graphic fashion the four cardiac chambers and _ valves.

Ex Output:
four