#include <stdio.h>

int main()
{
	FILE* f=fopen("fact.in","r");
	FILE* g=fopen("fact.out","w");
	int n,p,con=0,i,ok=1,ver;
	
	fscanf(f,"%d", &n);
	fclose(f);
	if (n!=0)
		for (i=5;ok;i+=5){
			ver=5;
			if (i%ver==0)
				do {
					con++;
					ver*=5;
					if (con==n)
						ok=0;
				}while ((i%ver==0) && (ok));
		}
	else 
		i=6;
	printf(g,"%d", i-=5);
	fclose(g);
	return 0;
}