#include <iostream>
#include <fstream>
using namespace std;

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

int main()
{
    int n, num = 0, cnt = 1;
    fin >> n;
    //cin >> n;
    for(long long i = 0; i < 100000000000000; i ++)
    {
        if(cnt % 5 == 0)
            num ++;
        if(cnt % 25 == 0)
            num ++;
        if(cnt % 125 == 0)
            num ++;
        if(cnt % 625 == 0)
            num ++;
        if(cnt % 3125 == 0)
            num ++;
        if(cnt % 15625 == 0)
            num ++;
        if(cnt % 78125 == 0)
            num ++;
        if(cnt % 390625 == 0)
            num ++;
        if(cnt % 1953125 == 0)
            num ++;
        if(cnt % 9765625 == 0)
            num ++;
        if(cnt % 48828125 == 0)
            num ++;
        if(cnt % 244140625 == 0)
            num ++;
        if(cnt % 1220703125 == 0)
            num ++;
        if(num >= n)
            break;
        cnt ++;
    }
    fout << cnt - 1;
    //cout << cnt;
}