#include<stdio.h>
#include<math.h>
int p,i,n=2,x;
FILE *f,*g;
int main ()
{

f=fopen("fact.in","r");
fscanf(f,"%d",&p);fclose(f);
g=fopen("fact.out","w");
if(p==0)fprintf(g,"%d",1);
	else if(p==1)fprintf(g,"%d",5);
	else{	while((p+n-1)*4*pow(5,n)/(pow(5,n)-1)-p*4*pow(5,n)/(pow(5,n)-1)>=5){n++;}
			x=(int(p*4*pow(5,n)/(pow(5,n)-1))/10)*10+5;
				fprintf(g,"%d",x);}

fclose(g);
return 0;

}