p=[0 for i in range(1001)]
p[0]=1
p[1]=1

for i in range(1001):
  if p[i]==0:
    cnt=2
    while cnt*i<1001:
      p[cnt*i]=1
      cnt+=1

N=int(input())

ans=0
for i in range(N+1):
  if p[i]==0:
    ans+=i
print(ans)