Halloween-Sale.py

'''
You wish to buy video games from the famous online video game store Mist.

Usually, all games are sold at the same price, p dollars. However, they are planning to have the seasonal Halloween Sale next month in which you can buy games at a cheaper price. Specifically, the first game you buy during the sale will be sold at p dollars, but every subsequent game you buy will be sold at exactly d dollars less than the cost of the previous one you bought. This will continue until the cost becomes less than or equal to m dollars, after which every game you buy will cost m dollars each.

For example, if p=20,d=3  and m=6 , then the following are the costs of the first 11 games you buy, in order:
    20,17,14,11,8,6,6,6,6,6,6

You have s dollars in your Mist wallet. How many games can you buy during the Halloween Sale?
'''
import sys

def howManyGames(p, d, m, s):
    # Return the number of games you can buy
    sum_ = p
    c = 1
    if p > s:
        return 0
    while (sum_ + p <= s):
        if p-d >= m:
            p = p-d
            sum_ += p
            c +=1
        else:
            p = m
            sum_ += p
            c += 1
    return c

if __name__ == "__main__":
    p, d, m, s = raw_input().strip().split(' ')
    p, d, m, s = [int(p), int(d), int(m), int(s)]
    answer = howManyGames(p, d, m, s)
    print answer