B"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. One day Petya came across an interval of numbers [a, xe2 x80 x89a xe2 x80 x89+ xe2 x80 x89l xe2 x80 x89- xe2 x80 x891]. Let F(x) be the number of lucky digits of number x. Find the minimum b (a xe2 x80 x89< xe2 x80 x89b) such, that F(a) = F(b), F(a xe2 x80 x89+ xe2 x80 x891) = F(b xe2 x80 x89+ xe2 x80 x891), ..., F(a xe2 x80 x89+ xe2 x80 x89l xe2 x80 x89- xe2 x80 x891) = F(b xe2 x80 x89+ xe2 x80 x89l xe2 x80 x89- xe2 x80 x891). The single line contains two integers a and l (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89a, xe2 x80 x89l xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89109) -- the interval's first number and the interval's length correspondingly. On the single line print number b -- the answer to the problem. Consider that [a, xe2 x80 x89b] denotes an interval of integers; this interval includes the boundaries. That is, "...