#include <bits/stdc++.h>

using namespace std;

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

int p,i,ans;

int zeros(int n)
{
    int rez=0;
    while(n)
    {
        rez+=n/5;
        n/=5;
    }
    return rez;
}

int main()
{
    fin>>p;
    for(i=1;i<=p*5;i<<=1);
    for(;i;i>>=1)
        if(zeros(ans+i)<p)
            ans+=i;
    if(zeros(ans+1)==p)fout<<ans+1;
    else fout<<-1;
    return 0;
}