N,M,P,Q=map(int,input().split())
l_y=2*M*Q+M*(12-Q)
ans=(N//l_y)*12
l=N%l_y
for m in range(1,13):
	ans+=1
	if P<=m and m<(P+Q):l-=2*M
	else:l-=M
	if l<=0:break
print(ans)