import sequtils,strutils
type
    jump = tuple[one : int, two : int, three : int]
const m = 1_000_000_007
var
    N,i,j : int
    procedure : seq[jump]
    pattern : jump 
procedure = @[(0,0,0),(1,0,0),(0,1,0),(1,1,1)]
N = stdin.readline.parseInt
if N < 3:
    echo 1
elif N == 3:
    echo 3
else:
    for i in 4..N:
        pattern.one = (procedure[i - 1].two + procedure[i - 1].three) mod m
        pattern.two = (procedure[i - 2].one + procedure[i - 2].three) mod m
        pattern.three = (procedure[i - 3].one + procedure[i - 3].two) mod m
        procedure.add(pattern)
    j = (procedure[N].one + procedure[N].two + procedure[N].three).int mod m
    echo j