#include <bits/stdc++.h>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
int n,p;
int nrzerouri(int n)
{   int nr1=0,nr2=0;
    for(int i=2;i<=n;i++)
    {   int x=i;
        while(x%2==0)
        { nr1++;
          x/=2;
        }
        while(x%5==0)
        {   nr2++;
            x/=5;
        }
    }
    return min(nr1,nr2);
}
int main()
{   fin>>p;
    bool gasit=0;
    int n=0;
    while(nrzerouri(n)<=p)
    {
        n++;
        if(nrzerouri(n)==p)
        {
            fout<<n;
            gasit=1;
            break;
    }
    }
    if(gasit==0) fout<<-1;
    return 0;
}