#include <cstdio>
FILE *f=fopen("fact.in","r");
FILE *g=fopen("fact.out","w");
using namespace std;
int zero(int x){int div=5,total=0;while(div<=x){total+=x/div;div*=5;}return total;}
void bsearch(int x)
{
    int m,li,lf,val;
    li=1;lf=500000000;
    while(li<=lf)
    {
        m=(li+lf)/2;val=zero(m);
        if(val>x)lf=m-1;
        else if(val<x)li=m+1;
        else if(val==x)lf=m-1;
    }
    if(zero(li)==x)fprintf(g,"%d",li);
    else fprintf(g,"-1");
}
int main()
{
    int n;
    fscanf(f,"%d",&n);bsearch(n);
    return 0;
}