def is_kadomatsu(a, b, c)
    return false if [a, b, c].uniq.size != 3
    if [a, b, c].min == b || [a, b, c].max == b
        return true
    else
        return false
    end
end

d, *h = $<.map(&:to_i)
INF = 10000000000
ans = INF
if d == 0
    p is_kadomatsu(*h) ? 0 : -1
    exit
end
tmp = h[1] - [h[0], h[2]].min
ans1 = tmp < 0 ? 0 : [tmp, 0].max / d + 1
ans = [ans, ans1].min if is_kadomatsu(h[0], [h[1] - d * ans1, 0].max, h[2])
tmp = h[0] - h[1]
tmp1 = tmp < 0 ? 0 : [tmp, 0].max / d + 1
tmp = h[2] - h[1]
tmp2 = tmp < 0 ? 0 : [tmp, 0].max / d + 1
ans2 = tmp1 + tmp2
ans = [ans, ans2].min if is_kadomatsu([h[0] - tmp1 * d, 0].max, h[1], [h[2] - tmp2 * d, 0].max)
p ans == INF ? -1 : ans