## https://yukicoder.me/problems/no/2480

import math

def main():
    N = int(input())

    sqrt_n = int(math.sqrt(N))

    answer = 0
    # l = 1, ... sqrt_n まで
    for l in range(2, sqrt_n + 1):
        x = N // l
        n = N - x * l
        if 1 <= n <= l - 1:
            answer += 1

    # X = 1,....sqrt_nまで
    for X in range(1, sqrt_n + 1):
        upper = N // X
        lower = N // (X + 1)
        lower = max(lower, sqrt_n)
        if upper <= lower:
            continue

        upper0 = (N - 1) // X 
        lower0 = (N + 1) // (X + 1)
        upper = min(upper0, upper)
        lower = max(lower + 1, lower0)
        if upper < lower:
            continue

        ans = upper - lower + 1
        answer += ans
    print(answer)





if __name__ == '__main__':
    main()