#include<fstream>
using namespace std;
unsigned long long int zerouri(unsigned long long int n) {
    unsigned int suma=0;
    unsigned long long x;
    x=n;
    while(n) {
        suma+=n%5;
        n/=5;
    }
    return (x-suma)/4;
}
int main ()
{long i=0,p,k,c=0;
ifstream f("fact.in");
f>>p;
f.close();
ofstream a("fact.out");
if (p==0)
	{a<<1;
     return 0;
	 a.close();
	}
i=p*4;
while (i<p*5 || c==0)
{k=zerouri(i);
 if (k==p)
	{a<<k;
     c=1;
	}
 if (k<p)
    i++;
 if (k>p)
	{a<<-1;
     c=1;
    }	 
} 
a.close();
return 0;
}