N, M, P, Q = map(int, input().split())


month_two = Q
Q = P + Q - 1
month_one = 12 - month_two

yearlost = (M * month_one) + ((2 * M) * month_two)
ans = (N // yearlost) * 12
remain = N % yearlost

if remain == 0:
    print(ans)
else:
    for i in range(1, 13):
        if Q >= i >= P:
            remain -= 2 * M
            ans += 1
        else:
            remain -= M
            ans += 1
        if remain <= 0:
            print(ans)
            break