#include<atcoder/all>
using namespace atcoder;

#include <bits/stdc++.h>
template<class T> inline bool chmin(T&a, T b){if(a > b){a = b; return true;}else{return false;}}
template<class T> inline bool chmax(T&a, T b){if(a < b){a = b; return true;}else{return false;}}
#define ll long long
#define double long double
#define rep(i,n) for(int i=0;i<(n);i++)
#define REP(i,n) for(int i=1;i<=(n);i++)
#define mod (ll)(1e9+7)
#define inf (ll)(3e18+7)
#define eps (double)(1e-9)
#define pi (double) acos(-1)
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
using namespace std;

int main() {
    ll n;
    cin >> n;
    vector<ll> p = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47};
    ll m = 1, i = 0;
    for(ll i = 0; i < 15; i++){
        m *= p[i];
        if(m > n){
            cout << i << endl;
            return 0;
        }
    }
    cout << 15 << endl;
}