### Hints and Guidelines

In order to solve the task, we read the input data, write a few conditional statements, do some calculations and print the result.

#### Processing the Input Data

From the task requirements we note that our program must have four lines from which we read the input data. The first three consist of integers and that is why the variables that will store their values will be of type int. We know that the fourth line will be a floating-point number, therefore, the variable we use will be of type double.

Out next step is to declare and initialize a variable in which we are going to calculate with how many liters the pool has filled up for the time the worker was absent. We do the calculations by summing the values of the flow rates of the two pipes and multiplying them by the hours that are given as an input data.