n,m = gets.split.map(&:to_i)
dp = Array.new(n + 1)
dp[0] = 0
dp[1] = 1
2.upto(n){|i|
    dp[i] = dp[i - 1] + dp[i - 2]
    }
x = dp[n] - m
if x < 0
    p -1
elsif x == 0
    p 0
else
    ans = 0
    (n - 2).downto(1){|i|
        if x >= dp[i]
            x -= dp[i]
            ans += 1
        end
        if x == 0
            break
        end
        }
    if x == 0
        p ans
    else
        p -1
    end
end