#include <bits/stdc++.h>
using namespace std;

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

typedef long long ll;
typedef long double ld;


void solve(){
    long number;
    int noOfZeros;
    in >> noOfZeros;
    number = 0;
    while(noOfZeros){
        number += 5;
        int crtNoOfZeros = 0;
        long tempNumber = number;
        while(tempNumber %5 == 0){
            crtNoOfZeros += 1;
            tempNumber /= 5;    
        }
            
        noOfZeros -= crtNoOfZeros;
    }
    out << number;
}

int main()
{
    ios_base::sync_with_stdio(false);cin.tie(0);
    solve();
    return 0;
}