$m=1e9+7;
$n=<>;
$1[1]=1;
$2[2]=1;
$1[3]=1;
$2[3]=1;
$3[3]=1;
for(4..$n){
	$1[$_]=($2[$_-1]+$3[$_-1])%$m;
	$2[$_]=($1[$_-2]+$3[$_-2])%$m;
	$3[$_]=($1[$_-3]+$2[$_-3])%$m;
}
print+($1[$n]+$2[$n]+$3[$n])%$m