def kadomatu?(a,b,c)
    (a!=c)&&((a<b&&b>c)||(a>b&&b<c))
end

def say(t)
    puts t;exit 0
end

def magic(h,d)
    [0,h-d].max
end

d,a,b,c = STDIN.read.split.map(&:to_i)

say 0 if kadomatu?(a,b,c)
say -1 if d == 0

a,c = c,a if a > c

l = [a,b,c].min

if a==b && b==c
    say -1 if l <= d
    say 3
end

if [a,b,c].uniq.size == 2
    if a==c
        if a < b
            say 1 if a>=1
            say -1
        else # a>b
            say 1 if kadomatu?(magic(a,d),b,c)
            say 2 if kadomatu?(magic(a,d),magic(b,d),c)
            say 3 if kadomatu?(magic(a,d*2),b,magic(c,d))
            say 5 if kadomatu?(magic(a,d*3),b,magic(c,d*2))
            say -1
        end
    end
    # a<c
    if a==b
        say 1 if a>=1
        say -1
    else
        # b==c
        say 1 if kadomatu?(a,b,magic(c,d))
        say 2 if kadomatu?(a,b,magic(c,d*2))
        say -1
    end
end
# a<b<c

result = []

result << (c-b+d-1)/d if kadomatu?(a,b,magic(c,(c-b+d-1)/d*d))
result << ((c-b+d-1)/d+1) if kadomatu?(a,b,magic(c,(c-b+d-1)/d*d+d))
result << (b-a+d-1)/d if kadomatu?(a,magic(b,(b-a+d-1)/d*d),c)
result << ((b-a+d-1)/d+1) if kadomatu?(a,magic(b,(b-a+d-1)/d*d+d),c)

say -1 if result.empty?
say result.min