#include <bits/stdc++.h>

using namespace std;

ifstream fin("fact.in");
ofstream fout("fact.out");

int findTrailingZeros(int n)
{
    int count = 0;
    for (int i = 5; n / i >= 1; i *= 5)
        count += n / i;

    return count;
}

int main()
{
    int n;
    fin >> n;
    for(long long int i = 1; i <= 10000000; i++)
    {
        if(findTrailingZeros(i) == n)
        {
            fout << i;
            break;
        }
    }
    return 0;
}