#include<stdio.h>
#define Nmax 1000000000
int nr_de_zero_factorial(int a)
{
    int i,p;
    p=0;
    for(i=1;i<=a;i++)
    	if(i%5==0)
    	{
    		p++;
    	}
    return p;}
int functie(int a, int b, int p)
{
	int c;
	c=(b-a)/2+a;
	if(nr_de_zero_factorial(c)>p)
		functie(a,c-1,p);
	else
	if(nr_de_zero_factorial(c)<p)
		functie(c+1,b,p);
	else
		return c;
}
main()
{
	FILE *myFile,*fp;
	int p,n,k,nr;
	myFile=fopen("fact.in","r");
	fscanf(myFile, "%d,", &p);
	fp=fopen("fact.out","w");
	functie(1,Nmax,p);
 	fprintf(fp,"%d\n",n);
	fclose(fp);
	fclose(myFile);

}