#include <iostream>
#include <fstream>
#define maxval 100000000
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int NmbOfZero(int i)
{
    long long zero=0;
    while(i)
    {
        zero+=i/5;
        i/=5;
    }
    return zero;
}
int main()
{
    long long p, pas=1<<30, i=0;
    in>>p;
    if(p==0)
    {
        out<<1<<"\n";
        return 0;
    }
    while(pas!=0)
    {
        if(NmbOfZero(i+pas)<p)
            i+=pas;
        pas/=2;
    }
    if(NmbOfZero(i+1)!=p)
    {
        out<<"-1\n";
        return 0;
    }
    out<<i+1<<"\n";
    return 0;
}