let n = Int(readLine()!)!
let pr = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53]
var x = 1, k = 0, ans = 0
let Max = 1000000000000000000
while x <= Max / pr[k] && x * pr[k] <= n{
    ans += 1
    x *= pr[k]; k += 1
}
print(ans)