#include <iostream>
#include <fstream>
#include <math.h>
using namespace std;
int T=1,a=0,c,b[21],P,i;
int main()
{ifstream f("fact.in",ios::in);
ofstream g("fact.out",ios::out);
f>>P;
for(i=1;i<=500;i++)
{           T=T*i;
while(T=0){
    T=T/10;
    b[i]=T%10;}
    for(i=1;i<=100;i++)
    if(b[i]=b[i+1]=0)
     a++;}
if (a=P) g<<i;
         else
         g<<-1;
         f.close();g.close();



return 0;
}