Cowboy Shootout

Wild Roger is tasked with shooting down 6 bottles with 6 shots as fast as possible. Here are the different types of shots he could make:

• He could use one pistol to shoot a bottle with a "Bang!" in 0.5 seconds.
• Or he could use both pistols at once with a "BangBang!" to shoot two bottles in 0.5 seconds.

Given a list of Bangs and BangBangs return the time (in seconds) it took to shoot down all 6 bottles. Make sure to only count Bangs and BangBangs. Anything else doesn't count.

Examples

roger_shots(["Bang!", "Bang!", "Bang!", "Bang!", "Bang!", "Bang!"]) ➞ 3

roger_shots(["Bang!", "Bang!", "Bang!", "Bang!", "BangBang!"]) ➞ 2.5

roger_shots(["Bang!", "BangBangBang!", "Boom!", "Bang!", "BangBang!", "BangBang!"]) ➞ 2

Notes

All the bottles will be shot down in all the tests.