Learn to write do$-$while loops.

Assignment: In developing an algorithm for a new fitness app, you're tasked with calculating the cumulative elevation gain for a $50-$step stair$-$climbing challenge. Each step increases in height exponentially, starting from $1$ meter for the first step and doubling the height increase for each subsequent step.

Given long variables totalElevation and step that have already been declared, use a do$-$while loop to calculate the total elevation gain over $50$ steps, with each step's elevation gain being twice the previous step's gain $($starting from $1$ meter for the first step$).$ Store this cumulative elevation in totalElevation.

For example, the elevation gain sequence will start $1,2,4,8,$ etc., doubling each time.