import sys; input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	N, M, P, Q = getlist()
	L = [0] * 12
	for i in range(P - 1, P - 1 + Q):
		L[i] = 1

	# print(L)
	cnt = 0
	while True:
		if L[cnt % 12] == 1:
			N -= 2 * M
		else:
			N -= M

		if N <= 0:
			print(cnt + 1)
			return

		cnt += 1

if __name__ == '__main__':
	main()