#yuki740

n,m,p,q=map(int,raw_input().split())
a=[]
for i in xrange(p):
 a.append(m)
for i in xrange(p,p+q):
 a.append(m*2)
for i in xrange(p+q,12):
 a.append(m)

x=0
while n>0:
 n-=a[x%12]
 x+=1
print x