#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <math.h>
#include <iomanip>
#include <string.h>
#define Maxim 200000000
using namespace std;

ifstream f("fact.in");
ofstream g("fact.out");



int main()
{   int n;
    f >> n;
    if(n==0)
        {g << "1\n";
        return 0;
        }
    int i,j,nr=0;
    for(i=5;nr<n;i+=5)
        {j=i;
        while(j%5==0)
            {nr++;
            j/=5;
            }
        }
    g << i-5 << '\n';
    return 0;
}