N = gets.to_i
M = 10**9+7

$dp = Array.new(N+3){[0]*4}
$dp[1][1] = $dp[2][2] = $dp[3][3] = 1
(1...N).each{|i|
  $dp[i+1][1] += ($dp[i][2] + $dp[i][3])%M
  $dp[i+2][2] += ($dp[i][1] + $dp[i][3])%M
  $dp[i+3][3] += ($dp[i][1] + $dp[i][2])%M
}

p$dp[N].sum%M