#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll MOD = (1e+9)+7;
const ll INF = (ll)1000000007 * 1000000007;
typedef pair<int, int> P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef long double ld;
typedef complex<ld> Point;
const ld eps = 1e-11;
const ld pi = acos(-1.0);
typedef pair<ll, ll> LP;
typedef pair<ld, ld> LDP;
int main() {
	int isp[1300];
	fill(isp, isp + 1300, 1);
	Rep(i, 2, 1300) {
		if (isp[i]) {
			for (int j = i * 2; j < 1300; j += i) {
				isp[j] = 0;
			}
		}
	}
	int n; cin >> n;
	int sum = 0;
	int used[1300] = {};
	for (int i = n; i >= 2; i--) {
		if (isp[i]&&(used[i]==0)) {
			used[i] = 1;
			int d = n / i;
			if (d == 1) {
				sum += i;
			}
			else if(d<i){
				bool f = true;
				for (int j = d; j >= 2; j--) {
					if (isp[j]&&(used[j]==0)) {
						int s = j;
						while (s <= n)s *= j;
						s /= j;
						if (s + i < i*j) {
							sum += i * j; used[j] = 1; f = false; break;
						}
					}
				}
				if (f) {
					sum += i;
				}
			}
			else {
				int s = i;
				while (s <= n)s *= i; s /= i;
				sum += s;
			}
		}
	}
	cout << sum << endl;
	return 0;
}