#include <iostream>
#include <fstream>

using namespace std;

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

int p,k2,k5,n=1,minim=0,cop;

int main()
{
    fin>>p;
    while(1)
    {
        cop=n;
        if(n%2==0)while(cop%2==0){k2++;cop/=2;}
        if(n%5==0)while(cop%5==0){k5++;cop/=5;}
        if(k2<k5)minim=k2;
        else minim=k5;
        if(minim==p)break;
        if(minim>p)break;
        ++n;
    }
    fout<<n;
    return 0;
}