n,m,p,q = map(int,input().split())
a = (n // (m*(12 + q)))*12
b = n % (m*(12 + q))
ml = [p+i for i in range(q)]
mon=1
while b > 0:
    a+=1
    if mon in ml:
        b-=m*2 
    else:
         b-=m
    mon+=1
print(a)