To solve the cipher, you must know the height and cycle of the puzzle. The height is simply the number of fence rails used to create it. In this example, we said that 3 fence rails were used, so the height is 3. The height will always be higher than 2 and no more than the number of letters in the ciphertext (in this case 21) or else the phrase will not be properly encoded; the height can thus be discovered by process of elimination if not known.