#include <cstdio>
#define MAX 30
using namespace std;
struct nr{
    int putere,zero;
}q[MAX];
int l,rez,i,j,k,kc,p,pc;
int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
    scanf("%d",&p);
    pc=p;
    q[0].putere=1;
    for(i=1;i<=13;++i)q[i].putere=q[i-1].putere*5;
    for(j=1;j<i;++j)
    {
        for(k=q[j-1].putere+1;k<=q[j].putere;++k)
            if(k%5==0)
            {
                kc=k;
                while(kc%5==0){
                kc/=5;
                q[j].zero++;
                }
            }
        q[j].zero+=q[j-1].zero;
    }
    for(j=i-1;j>=1;j--)
        if(p>=q[j].zero){
            rez+=(p/q[j].zero)*q[j].putere;
            p%=q[j].zero;
    }
    if(pc==0){printf("1");return 0;}
    if(pc==5){printf("-1");return 0;}
    printf("%d",rez);
    return 0;
}