n = int(input())

dc = {'11':1, '12':1, '21':0}

for i in range(n-2):
    a = dc['11']
    b = dc['12']
    c = dc['21']
    dc['12'] = a+c
    dc['11'] = c
    dc['21'] = b
    
a = (dc['11']+dc['12']+dc['21'])%(10**9+7)
print(a)