import math
import sys
def S(): return sys.stdin.readline().rstrip()
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int, sys.stdin.readline().rstrip().split())
def LI(): return list(map(int, sys.stdin.readline().rstrip().split()))
def LS(): return list(sys.stdin.readline().rstrip().split())

n, m, p, q = MI()

ans = 0
while n> 0:
    ans += 1
    if p-1 <= (ans-1)%12 <= p+q-2:
        n -= 2*m
    else:
        n -= m

print(ans)