era = [1] * 100001
era[0], era[1] = 0, 0

MAX_VALUE = int(input())
ans = 0
for i in range(2, 100001):
	if not era[i]:
		continue
	for j in range(2*i, 100001, i):
		era[j] = 0
	
	ii = i * i
	while ii <= MAX_VALUE:
		ans += ii
		ii *= i

print(ans)
# print(era[:1000])