## function1 – Function from points (challenge)

Write a program that given a pair of assignments f(x₁) = y₁ and f(x₂) = y₂, calculates the function f, given by f(x) = ax + b.

Example 1. If f(0) = 2 and f(2) = 3 then f(x) = x/2 + 2.

Example 2. If f(1) = 6 and f(4) = 12 then f(x) = 2x + 4. ### Input and output

The input contains a single line with 4 numbers x₁, y₁, x₂ and y₂

where 0 ≤ x₁, y₁, x₂, y₂ ≤ 100

The output should contain a single line with a function description to the standard output in the form `f(x) = A.A*x + B.B` where `A.A` and `B.B` are the coefficients rounded to one decimal place.

Inputs are given so that it is always possible to produce such function.

#### Example input 1

``````0 2 2 3
``````

#### Example output 1

``````f(x) = 0.5*x + 2.0
``````

#### Example input 2

``````1 6 4 12
``````

#### Example output 2

``````f(x) = 2.0*x + 4.0
``````

### Scoring

• 2/60: works for the above examples but produces output in an incorrect format
• 4/60: works for the above examples and produces output in the correct format
• 60/60: produce output in the correct format with the correct coefficients

try first: pi

try next: function