CONO-SUR 1997 Problem 1

We have $98$ cards, in each one we will write one of the numbers: $1, 2, 3, 4,...., 97, 98$ . We can order the $98$ cards, in a sequence such that two consecutive numbers $X$ and $Y$ and the number $X - Y$ is greater than $48$ , determine how and how many ways we can make this sequence!!