n, m, p, q = map(int, input().split())
for i in range(1, n+1):
    j = i
    i %= 12
    if i == 0:
        i = 12
    if p <= i <= p+q-1:
        n -= 2*m
    else:
        n -= m
    if n <= 0:
        print(j)
        exit()