n=int(input())
N=10**5
spf=[0]*(N+1)
prime=[]
for m in range(2,N+1):
 if spf[m]<1:spf[m]=m;prime+=[m]
 for p in prime:
  if p>spf[m] or p*m>N:break
  spf[p*m]=p
ans=0
for p in prime:
  if p*p>n:
    break
  np=p
  for i in range(2,n):
    np*=p
    if np>n:
      break
    ans+=np
print(ans)