#include <fstream>
#include <algorithm>

using namespace std;

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

long long n, nr, x, p, i;

int main()
{   f >> n;
    for ( i = 1; i <= 1000000; i++ ){
        x = i;
        p = 1;
        while ( x % 5 == 0 ){
            p++;
            x = x / 5;
        }
        nr = nr + p;
        if ( nr >= n )
            break;
    }
    if ( n == 0 )
        g << "1";
    else
        g << i * 5;



    return 0;
}