#include <cstdio>
#include<cmath>
using namespace std;

int numar (int n)
{
    int p=5,nr=0;
    while(p<=n)
    {
        nr=nr+n/p;
        p*=5;
    }
    return nr;
}
int main()
{
    int d,st=1,dr=1000000000,mij,k,sol;
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
    scanf("%d",&k);
    while(st<=dr)
    {mij=(st+dr)/2;
        d=numar(mij);
        if(d>=k)
        { sol=mij;
           dr=mij-1;
        }
        else if(d<k) st=mij+1;
    }
     if(numar(sol)==k) printf("%d\n",sol); else printf("-1\n");
    return 0;
}