#include<stdio.h>
#define infile "factorial.in"
#define outfile "factorial.out"

long n;

void read()
{
	scanf("%ld",&n);
}
void solve()
{
	long i,x,nr=0;
	for(i=2;i<=1000000000;i++)
		{
			x=i;
			while(x%5==0)
			{
				nr++;
				x=x/5;
			}
			if(nr>=n)
			{
				printf("%ld",i);
				break;
			}
		}
}
int main()
{
	freopen(infile,"r",stdin);
	freopen(outfile,"w",stdout);
	read();
	solve();
	fclose(stdin);
	fclose(stdout);
	return 0;
}