#!/bin/python3

import sys

def howManyGames(p, d, m, s):
    # Return the number of games you can buy
    if s < p:
        return 0
    else:
        quotient = s // p
        diffquotient = (p - m) // d

        if quotient <= diffquotient:
            cost = (quotient * p) - (d * quotient * (quotient - 1) // 2)
            newP = p - (quotient * d)
            return quotient + howManyGames(newP, d, m, s - cost)

        cost = (diffquotient * p) - (d * diffquotient * (diffquotient - 1) // 2)
        newP = p - (diffquotient * d)

        if newP > m:
            cost += newP
            newP = m

            if quotient > diffquotient + 1:
                cost += m * (quotient - diffquotient - 1)

            return quotient + howManyGames(newP, d, m, s - cost)

        cost += m * (quotient - diffquotient)
        newP = m

        return quotient + howManyGames(newP, d, m, s - cost)


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