n,m,p,q=map(int,input().split())
fall_year=m*(12-q)+2*m*q
ans=12*(n//fall_year)
rem=n%fall_year
fall=[m]*12
for i in range(p-1,p+q-1):
    fall[i]*=2
now=0
while rem>0:
    rem-=fall[now]
    ans+=1
    now+=1
print(ans)