#include<stdio.h>
using namespace std;
long int p,i=1,s,putere,x;
int main()
{
    FILE*f=fopen("fact.in","r");
    FILE*g=fopen("fact.out","w");
    fscanf(f,"%d",&p);
    while(s<p)
    {   if(i==1) i=i+4;
        else i=i+5;
        putere=0;x=i;
        while((x>1)&&(x%5==0))
        {
            putere++;x=x/5;
        }
        s=s+putere;
    }
    if(s==p) fprintf(g,"%d",i);
    else fprintf(g,"-1");
    fclose(f);
    fclose(g);
    return 0;
}