# [Ceoi2013]board

时间限制：1s 空间限制：256MB

### 题目描述

Mirko and Slavko have a new board game. The game board resembles a complete infinite binary tree. More precisely, the board consists of nodes and two-way roads connecting them. The root node is located at the

top of the board and we say it is at

*level zero*. Each node has exactly two children, the*left child*and the*right child*, located in the lower-left and the lower-right directions of the parent node. The level of a

child node is one greater than the level of the parent node. In addition to roads connecting a parent node with its children, there are roads connecting all of the nodes at a particular level – for each level, starting from the leftmost node, there is a road connecting each node to the next node to the right on the same level.

**Figure 1: The second test example below**

Each

*path*through the game board is a sequence of steps, each moving from a node to a different node viaa single road. Each step can be described by a single character as follows:

· character „1‟ describes moving from a node to its left child,

· character „2‟ describes moving from a node to its right child,

· character „U‟ describes moving from a node to its parent,

· character „L‟ describes moving from a node to the next node to the left on the same level,

· character „R‟ describes moving from a node to the next node to the right on the same level.

For example, if we were to start at the root node and take the sequence of steps „221LU‟ we would end up in the node denoted with the letter „A‟ in the figure above.

**TASK**

Write a program that will, given two nodes on the board, find the smallest number of steps needed to go from one node to the other. The two nodes are given by specifying paths from the root node to them. If the two paths lead to the same node, the answer is zero.

### 输入格式

The first line of input contains a sequence of at most 100 000 characters – the path from the root to the first node.

The second line of input contains a sequence of at most 100 000 characters – the path from the root to the second node.

The two paths will be valid (it will be possible to make every move in both sequences).

### 输出格式

The first and only line of output should contain a single integer - the smallest number of steps needed to go from one node to the other.

### 样例输入

221LU 12L2

### 样例输出

3

### 提示

没有写明提示

### 题目来源

没有写明来源