#include <bits/stdc++.h>
using namespace std;
using ll = long long;

template<typename T>
T MUL(T a, T b){
    T res;
    return __builtin_mul_overflow(a, b, &res)? std::numeric_limits<T>::max() : res;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    vector<bool> tb(101);
    ll n, v = 1;
    int ans = 0;
    cin >> n;
    for(int i = 2; i <= 100 && v <= n; i++){
        if(tb[i]) continue;
        v = MUL(v, (ll)i);
        if(v <= n) ans++;
        for(int j = i; j <= 100; j += i){
            tb[j] = true;
        }
    }
    cout << ans << '\n';
}