Petya loves lucky numbers. We all know that lucky numbers are the positive integers whose decimal representations contain only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.
Unfortunately, not all numbers are lucky. Petya calls a number nearly lucky if the number of lucky digits in it is a lucky number. He wonders whether number n is a nearly lucky number.
Output
Print on the single line "
YES" if
n is a nearly lucky number. Otherwise, print "
NO" (without the quotes).
Note
In the first sample there are 3 lucky digits (first one and last two), so the answer is "
NO".
In the second sample there are 7 lucky digits, 7 is lucky number, so the answer is "
YES".
In the third sample there are no lucky digits, so the answer is "
NO".