def eratosthenes(limit: int, minLimit: int = None):
    if minLimit and (minLimit < 0 or minLimit > limit):
        raise ValueError("incorrect minLimit")
    isPrime = [True] * max(limit + 1, 2)
    isPrime[0] = False
    isPrime[1] = False
    for p in range(2, limit + 1):
        if not isPrime[p]:
            continue
        for i in range(p * p, limit + 1, p):
            isPrime[i] = False
    if minLimit:
        return [i for i, x in enumerate(isPrime[minLimit:], start=minLimit) if x]
    else:
        return [i for i, x in enumerate(isPrime) if x]

N = int(input())
l = eratosthenes(int(N**0.5))
#print(l)
ans = 0
for i in l:
    tmp = i**2
    for j in range(40):
        if tmp <= N:
            ans += tmp
        else:
            break
        tmp *= i
print(ans)