def solve(d, h1, h2, h3):
    if h1 == h2 == h3:
        if max(0, h1 - d) == max(0, h1 - 2*d):
            return -1
        return 3
    if d == 0:
        if h1 == h2 or h2 == h3 or h3 == h1:
            return -1
        if max(h1, h2, h3) == h2 or min(h1, h2, h3) == h2:
            return 0
        else:
            return -1 
    if h1 == h3:
        if h1 == 0:
            return -1
        if h2 > h1:
            return 1
        # h2 < h1
        if h1 - d > h2:
            return 1
        if max(0, h1 - d) == h2:
            if h2 > 0:
                return 2
            else:
                return -1
        if max(0, h1 - d) == max(0, h2 - d):
            return -1
        return 2
    if h1 > h3:
        h1, h3 = h3, h1
    # h1 < h3 に強制的に変更
    if h1 > h2:
        return 0
    if h3 < h2:
        return 0
    if h1 == h2:
        if h2 > 0:
            return 1
        else:
            return 0
    if h3 == h2:
        if max(0, h2 - d) < h1:
            return 1
        if max(0, h3 - d) != h1:
            return 1
        if max(0, h3 - d * 2) != h1:
            return 2
        if max(0, h3 - d) != max(0, h1 - d):
            return 2
        if max(0, h2 - d * 2) < h1:
            return 2
        return -1
    # h1 < h2 < h3 のケース
    s3 = (h3 - h2) // d + 1
    h33 = max(0, h3 - s3 * d)
    if h33 == h1:
        if h1 > 0:
            s3 += 1
        else:
            s3 = float('inf')
    s2 = (h2 - h1) // d + 1
    h22 = max(0, h2 - s2 * d)
    if h22 == h1:
        if h1 > 0:
            s2 += 1
        else:
            s2 = float('inf')
    s = min(s3, s2)
    if s == float('inf'):
        return -1
    else:
        return s

d = int(input())
h1 = int(input())
h2 = int(input())
h3 = int(input())
print(solve(d, h1, h2, h3))