IsPrime = [True for _ in range(1001)]
IsPrime[0] = IsPrime[1] = False
for i in range(2, 1001):
    if IsPrime[i]:
        for j in range(i + i, 1001, i):
            IsPrime[j] = False

n = int(input())
ans = 0
for i in range(n + 1):
    if IsPrime[i]:
        ans += i
print(ans)