CF340A.The Wall

Iahub and his friend Floyd have started painting a wall. Iahub is painting the wall red and Floyd is painting it pink. You can consider the wall being made of a very large number of bricks, numbered 1, 2, 3 and so on.

Iahub has the following scheme of painting: he skips x - 1 consecutive bricks, then he paints the x-th one. That is, he'll paint bricks x, 2·x, 3·x and so on red. Similarly, Floyd skips y - 1 consecutive bricks, then he paints the y-th one. Hence he'll paint bricks y, 2·y, 3·y and so on pink.

After painting the wall all day, the boys observed that some bricks are painted both red and pink. Iahub has a lucky number a and Floyd has a lucky number b. Boys wonder how many bricks numbered no less than a and no greater than b are painted both red and pink. This is exactly your task: compute and print the answer to the question.

伊阿胡布和他的朋友弗洛伊德开始粉刷一堵墙。伊阿胡布将墙涂成红色，而弗洛伊德则将其涂成粉色。你可以将这堵墙视为由大量砖块构成，砖块编号依次为 $1, 2, 3, \dots$。

伊阿胡布采用如下涂刷方案：他跳过 $x-1$ 块连续的砖，然后将第 $x$ 块砖涂色。也就是说，他将把编号为 $x,\, 2\cdot x,\, 3\cdot x,\, \dots$ 的砖涂成红色。类似地，弗洛伊德跳过 $y-1$ 块连续的砖，然后将第 $y$ 块砖涂色。因此，他将把编号为 $y,\, 2\cdot y,\, 3\cdot y,\, \dots$ 的砖涂成粉色。

经过一整天的粉刷后，两个男孩发现某些砖块同时被涂成了红色和粉色。伊阿胡布有一个幸运数字 $a$，弗洛伊德有一个幸运数字 $b$。他们想知道：编号在 $a$ 到 $b$（含端点）之间的砖块中，有多少块同时被涂成红色和粉色？这正是你的任务：计算并输出该问题的答案。

The input will have a single line containing four integers in this order: x, y, a, b. (1 ≤ x, y ≤ 1000, 1 ≤ a, b ≤ 2·109, a ≤ b).

输入为一行，包含四个整数，顺序为：$x$、$y$、$a$、$b$。（$1 \le x,\,y \le 1000$，$1 \le a,\,b \le 2\cdot10^9$，且 $a \le b$）

Output a single integer — the number of bricks numbered no less than a and no greater than b that are painted both red and pink.

输出一个整数——编号在 $a$ 到 $b$（含）之间、且同时被涂成红色和粉色的砖块的数量。

Let's look at the bricks from a to b (a = 6, b = 18). The bricks colored in red are numbered 6, 8, 10, 12, 14, 16, 18. The bricks colored in pink are numbered 6, 9, 12, 15, 18. The bricks colored in both red and pink are numbered with 6, 12 and 18.

我们来观察从 $a$ 到 $b$ 的砖块（$a = 6$，$b = 18$）。红色砖块编号为 6、8、10、12、14、16、18；粉色砖块编号为 6、9、12、15、18；同时被染成红色和粉色的砖块编号为 6、12 和 18。