proc getchar_unlocked():char {. importc:"getchar_unlocked",header: "<stdio.h>" .}
proc scan(): int =
  while true:
    let k = getchar_unlocked()
    if k < '0': break
    result = 10 * result + k.ord - '0'.ord

const MOD = 1_0000_0000_7
let n = scan()
var dp1 = newSeq[int](n.max(10)+1)
var dp2 = newSeq[int](n.max(10)+1)
var dp3 = newSeq[int](n.max(10)+1)
dp1[1] = 1 # 1
dp2[2] = 1 # 2
dp3[3] = 1 # 3
for i in 1..n:
  if i+1<dp1.len: dp1[i+1] = (dp1[i+1] + dp2[i] + dp3[i]) mod MOD
  if i+2<dp2.len: dp2[i+2] = (dp2[i+2] + dp1[i] + dp3[i]) mod MOD
  if i+3<dp3.len: dp3[i+3] = (dp3[i+3] + dp2[i] + dp1[i]) mod MOD
# for i in 1..10:
  # echo [i,dp1[i],dp2[i],dp3[i],dp1[i] + dp2[i] + dp3[i]]
echo dp1[n] + dp2[n] + dp3[n]