#include <cstdio>
#include <cmath>
using namespace std;

FILE *f=fopen ("fact.in","r");
FILE *g=fopen ("fact.out","w");

int n;

int binarys (int a,int b){
	int m,k,v;
	m=(a+b)/2;
	v=m; k=0;
	while (v>0){
		k+=v/5;
		v/=5;
	}
	if (k==n){
		return m-m%5;
	}
	else{
		if (k<n){
			return binarys(m+1,b);
		}
		else{
			return binarys (a,m-1);
		}
	}
	if (a>b){
		return -1;
	}
}

int main(){
    int st=0,dr=500000000,c;
    
	fscanf(f,"%d",&n);
    
	if (n<0) {
        fprintf(g,"-1");
    }
    else{
		if (n==0){
			fprintf(g,"1");
		}
		else{
			c=binarys(st,dr);
			fprintf (g,"%d",c);
		}
	}
    return 0 ;
}