def solve(n)
    return 0 if n < 2
    
    ans = n-1
    
    num = n
    (1..([(n-1)/2,4000].min)).each do |i|
        ans -= 2 if (num).odd?
        num*=n-i
        num/=i+1
    end
    ans
end

while cin = gets
    p solve(cin.to_i)
end