d = int(input())
h = [0] * 3
h[0] = int(input())
h[1] = int(input())
h[2] = int(input())

if d == 0:
    if h[0] > h[1] and h[2] > h[1] :
        if h[0] != h[2]:
            ans = 0
    elif h[0] < h[1] and h[2] < h[1]:
        if h[0] != h[2]:
            ans = 0
    else:
        ans = -1
    print(ans)
    exit()

if h[0] > h[1] and h[2] > h[1] :
    if h[0] != h[2]:
        ans = 0
    elif (h[0] - h[1]) > d:
        ans = 1
    elif h[0] - h[1] == d:
        if 2 * d == h[0]:
            ans = -1
        else:
            ans = 5
    else:
        if h[0] == d:
            ans = -1
        else:
            ans = 3
    print(ans)
    exit()

elif h[0] < h[1] and h[2] < h[1]:
    if h[0] != h[2]:
        ans = 0
    elif h[0] == 0 and h[2] == 0:
        ans = -1
    else:
        ans = 1
    print(ans)
    exit()

if h[2] >= h[0]:
    tmp = h[0]
    h[0] = h[2]
    h[2] = tmp

if min(h) == max(h):
    if min(h) <= d:
        ans = -1
    else:
        ans = 3
    print(ans)
    exit()

if h[2] == 0:
    ans = (h[0]-h[1]) // d + 1
    if h[0] == ans * d:
        ans = -1
    print(ans)
    exit()

if (h[0] - h[1]) == (h[1] - h[2]):
    ans = (h[0]-h[1]) // d + 1
    if h[0] == 2 * d:
        ans = -1
    print(ans)
    exit()

if (h[0] - h[1]) > (h[1] - h[2]):
    ans = (h[1]-h[2]) // d + 1
    #if (h[1]-h[2]) % d == 0:
    #    ans -= 1
    print(ans)
    exit()
else:
    ans = (h[0]-h[1]) // d + 1
    if h[0] == 2 * d:
        ans = -1
    print(ans)
    exit()