import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################


n = ni()

N = int(n ** 0.5 + 100)

A = [0] * N
ans = 0
for i in range(2, N):
    if A[i] == 0:
        x = i * i
        while x <= n:
            ans += x
            x *= i
        for j in range(i * 2, N, i):
            A[j] = 1

print(ans)