n = gets.to_i
a = Array.new(n)
a[0] = [0,1,0]
MOD = 1000000007
1.upto(n - 1){|i|
    a[i] = Array.new(3)
    a[i][0] = (a[i - 1][1] + a[i - 1][2]) % MOD
    a[i][1] = a[i - 1][0] % MOD
    a[i][2] = a[i - 1][1] % MOD
    }
p a[n - 1].inject(:+) % MOD