#include <bits/stdc++.h>
using namespace std;
int main()
{
    int n,maxn = 0;
    cin >> n;
    for (int i = 2; i <= n; i++)
        while (n % i == 0)
        {
            n /= i;
            maxn = max(maxn,i);
        }
    cout << maxn;
    
    return 0;
}