N = int(input())
L = []
M = []
T = 0
limit = int(N ** 0.5)
for n in range(2, limit + 1):
    sushu = True
    for b in range(2, int(n ** 0.5) + 1):
        if n % b == 0:
            sushu = False
            break
    if sushu:
        L.append(n)

for x in L:
    for c in range(2,N):
        a = x ** c
        if a <= N:
            M.append(a)
        else:
            break
for b in M:
    T = T + b
print(T)