ans=0
N=int(input())
for i in range(2,200000):
    prime=True
    for j in range(2,i):
        if i%j==0:
            prime=False
            break
    if prime:
        for j in range(2,40):
            if pow(i,j)<=N:
                ans+=pow(i,j)
            else:
                break
print(ans)