Given is a positive integer N. How many tuples (A,B,C) of positive integers satisfy A \times B + C = N?

Constraints

* 2 \leq N \leq 10^6
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


N


Output

Print the answer.

Examples

Input

3


Output

3


Input

100


Output

473


Input

1000000


Output

13969985
FAST_IO = 0
if FAST_IO:
    import io, sys, atexit
    rr = iter(sys.stdin.read().splitlines()).next
    sys.stdout = _OUTPUT_BUFFER = io.BytesIO()

    @atexit.register
    def write():
        sys.__stdout__.write(_OUTPUT_BUFFER.getvalue())
else:
    rr = raw_input
rri = lambda: int(rr())
rrm = lambda: map(int, rr().split())
rrmm = lambda n: [rrm() for _ in xrange(n)]

####
MOD = 10**9 + 7
YES, NO, IMP = "YES", "NO", "IMPOSSIBLE"
from collections import defaultdict as ddic

def solve(N):
    # AB + C = N
    # C = 1.. N-1
    ds = [2] * (N + 1)
    ds[0] = ds[1] = 1
    for i in xrange(2, N + 1):
        for j in xrange(2*i, N + 1, i):
            ds[j] += 1

    return sum(ds[i] for i in xrange(1, N))
    
N = rri()
print solve(N)
