#include <cstdio>

using namespace std;

int main()
{
    freopen("fact.in", "r", stdin);
    freopen("fact.out", "w", stdout);

    int n;

    scanf("%d", &n);

    int doi, cinci;

    doi = cinci = 0;

    int nr = 1;

    while(true)
    {
        int tmp = nr;

        while(tmp % 2 == 0)
        {
            doi++;
            tmp /= 2;
        }
        while(tmp % 5 == 0)
        {
            cinci++;
            tmp /= 5;
        }

        if(doi >= n && cinci >= n)
        {
            printf("%d", nr);
            return 0;
        }

        nr++;
    }

    return 0;
}