I am new to MySQL and I need your help. I have a table with similar data

```none
---------------------------------------------------
|RobotPosX|RobotPosY|RobotPosDir|RobotShortestPath|
---------------------------------------------------
|0.1      |   0.2   |      15   |       1456      |
|0.2      |   0.3   |      30   |       1456      |
|0.54     |   0.67  |      15   |       1456      |
|0.68     |   0.98  |      22   |       1234      |
|0.36     |   0.65  |      45   |       1234      |
|0.65     |   0.57  |      68   |       1456      |
|0.65     |   0.57  |      68   |       2556      |
|0.79     |   0.86  |      90   |       1456      |                 
---------------------------------------------------

```

As you can see there are repeated values in the column RobotShortestPath, But they are important. Each number represent a specific task. If the number repeats consecutively(ex: 1456), it means that Robot is performing that task, and when the number changes(ex: 1234) it means that it has switched to another task. And if the previous number(ex:1456) appears again it also means that robot is performing a new task(1456) after done with earlier task(1234). 

So where I am stuck is I am unable to get no of tasks performed. I have used several things from my minimum knowledge like COUNT, GROUP BY but nothing seem to work. 

Here the no.of tasks performed are 5 actually, but whatever I do I get only 3 as result.