def is_valid (n)
    damm = [ [0,3,1,7,5,9,8,6,4,2],
             [7,0,9,2,1,5,4,8,6,3],
             [4,2,0,6,8,7,1,3,5,9],
             [1,7,5,0,9,8,3,4,2,6],
             [6,1,2,3,0,4,5,9,7,8],
             [3,6,7,4,2,0,9,5,8,1],
             [5,8,6,9,7,2,0,1,3,4],
             [8,9,4,5,3,6,2,0,1,7],
             [9,4,3,8,6,1,7,2,0,5],
             [2,5,8,1,4,3,6,7,9,0] ]
    temp = 0
    for ch in n.digits.reverse
        temp = damm[temp][ch]
    end
    return temp == 0
end

puts("Valid numbers between 5700 and 5800 are:")
for i in 5700..5800
    if is_valid(i)
        printf("%d ", i)
    end
end
puts("")