n = int(input())
precision = (n+100)//4
unit = 10**precision
def isqrt(n): #binary search between 0 and n
lo = 0
hi = n
mi = 0
while lo<hi:
mi = (lo+hi+1)//2
test = mi*mi
if test > n:
hi = mi - 1
elif test < n:
lo = mi
else:
lo = hi = mi
return lo
enlarged_sqrt5 = isqrt(5*unit*unit)
enlarged_phi = (unit + enlarged_sqrt5)//2
enlarged_phi_to_n = enlarged_phi**n//unit**(n-1)
print((enlarged_phi_to_n+unit//2)//enlarged_sqrt5)
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