#include <iostream>
#include <fstream>
using namespace std;
int n;
long long int a=10000000000;
int main()
{
    ifstream cin("factorial.in");
    ofstream cout("factorial.out");
    cin>>n;
    if(n==0)
    {
        cout<<1;
    }
    else for(int i=5;i<=a;i+=5)
    {
            if(i/5+i/25==n)
            {
                cout<<i;
                break;
            }
    }
}