import math
N = int(input())
a = [2]
for i in range(2,N):
    c = []
    for j in range(len(a)):
        b = math.gcd(a[j],i)
        if b >= 2:
            c.append(a[j])
    if sum(c)<= i:
        for j in range(len(c)):
            a.remove(c[j])
        a.append(i)
print(sum(a))