Taxi Journey

A taxi journey costs $3 for the first kilometer travelled. However, all kilometers travelled after that will cost $2 each.

Create a function which returns the distance that the taxi must've travelled, given the cost as a parameter.

Examples

journey_distance(3) ➞ 1
# The first kilometer costs $3

journey_distance(9) ➞ 4
# The first kilometer costs $3 plus the other three kilometers (costing $2 each)

journey_distance(5) ➞ 2

Notes

• The input tests are valid integers >= 0.
• The output will always be a whole number.
• Remember that you are calculating the distance from the cost, not the other way around!