Minimum Switches Between Actions

You are given a sequence of actions performed by a robot. Each character in the sequence is either P (for picking an object) or L (for placing an object). The task is to compute the minimum number of switches between the two actions. A switch is defined as a change from one action to the other (i.e. from P to L or from L to P).

For example, if the input sequence is PPPLLPPPLL, the switches occur between the groups of characters as follows: from PPP to LL (1 switch), from LL to PP (2 switches), and from PP to LL (3 switches), resulting in a total of 3 switches.

If the sequence is empty or has only one type of character, the answer is 0. Mathematically, if we denote the sequence by \( s = s_1s_2 \ldots s_n \), then the answer can be computed as:

[ \text{switches}(s) = \sum_{i=2}^{n} \mathbf{1}{{s_i \neq s{i-1}}}, ]

where \( \mathbf{1}_{\{\cdot\}} \) is the indicator function.

inputFormat

The input consists of a single line, which is a string representing the sequence of actions. The string only contains the characters P and L and may be empty.

outputFormat

Output a single integer representing the number of switches between picking and placing actions.

PPPLLPPPLL

3