import math

d = int(input())
H = []
H.append(int(input()))
H.append(int(input()))
H.append(int(input()))

if H[1] == 0 and (H[0] == H[1] or H[1] == H[2]):
    print(-1)
    exit()

if H[0] == H[2] and H[0] == 0:
    print(-1)
    exit()

if (H[1] == max(H) or H[1] == min(H)) and (H[0] != H[2]):
    print(0)
    exit()

if d == 0:
    print(-1)
    exit()


cnt = 0
if H[0] == H[2]:
    H[2] = max(H[2]-d, 0)
    cnt += 1

if H[0] < H[2]:
    H[0], H[2] = H[2], H[0]

diff = 0
tar = 0
if H[2] == 0:
    diff = H[0] - H[1]
    tar = 0
else:
    diff = min(H[0] - H[1], H[1] - H[2])
    if H[0] - H[1] < H[1] - H[2]:
        tar = 0
    else:
        tar = 1

cnt += int(math.ceil((diff+0.5)/d))
H[tar] = max(H[tar] - d*cnt, 0)

if H[0] == H[1] or H[1] == H[2] or H[0] == H[2]:
    print(-1)
else:
    print(cnt)