CF262A Roma and Lucky Numbers

Roma (a popular Russian name that means 'Roman') loves the Little Lvov Elephant's lucky numbers. Let us remind you that lucky numbers are positive integers whose decimal representation only contains lucky digits $ 4 $ and $ 7 $ . For example, numbers $ 47 $ , $ 744 $ , $ 4 $ are lucky and $ 5 $ , $ 17 $ , $ 467 $ are not. Roma's got $ n $ positive integers. He wonders, how many of those integers have not more than $ k $ lucky digits? Help him, write the program that solves the problem.

The first line contains two integers $ n $ , $ k $ $ (1

In a single line print a single integer — the answer to the problem.

In the first sample all numbers contain at most four lucky digits, so the answer is $ 3 $ . In the second sample number $ 447 $ doesn't fit in, as it contains more than two lucky digits. All other numbers are fine, so the answer is $ 2 $ .