N=int(input())
c=10**6
D=[1]*c
D[0]=0
D[1]=0
E=[]
for i in range(2,c):
  if D[i]==1:
    E.append(i)
    d=i
    while d+i<c:
      d+=i
      D[d]=0

ans=0
for e in E:
  now=e 
  if e**2>N:
    break
  while True:
    now*=e 
    if now<=N:
      ans+=now 
    else:
      break 
print(ans)