fun main() {
    val n = readLine()!!.toInt()

    val dp = Array(3) { Array(n+1) { 0L } }
    dp[0][0] = 1

    val MOD = 1_000_000_007
    for (i in 1 .. n) {
        dp[0][i] = (dp[1][i-1] + dp[2][i-1]) % MOD
        dp[1][i] = dp[0][i-1]
        dp[2][i] = dp[1][i-1]
    }

    val ans = dp.sumOf { it.last() } % MOD
    println(ans)
}