n,m,p,q = map(int,input().split())
month = list(range(1,13))
target = list(range(p,p+q))
index = 0
count=0
while n>0:
    #print(index)
    now_m = month[index]
    if now_m in target:
        n-=2*m
    else:
        n-=m
    index+=1
    index%=12
    count+=1
print(count)