#include <cstdio>
using namespace std;

int p,i,ok,x,k;
int main ()
{
    freopen("fact.in", "r", stdin);
    freopen("fact.out", "w", stdout);
    scanf("%d", &p);
    if(p==0) printf("1");
    else
    {
        ok=0;
        for(i=5;ok<p;i=i+5)
        {
            k=0;
            x=i;
            while(x%5==0)
            {
                x=x/5;
                ++k;
            }
            ok=ok+k;
        }
        i=i-5;
        if(ok==p)
            printf("%d", i);
        else printf("-1");

    }
    return 0;
}