#include<fstream.h>
#include<stdio.h>
FILE *in,*out;

int cate(int x)
	{
	int hmm=0;
	while(x%5==0 && x!=0)
		{
		x=x/5;
		hmm=hmm+1;
		}
	return hmm;

	}
int main(void)
{
long p,a=10,suma=2;
in=fopen("fact.in", "r");
out=fopen("fact.out","w");
fscanf(in,"%d",&p);
fclose(in);
if(p==0) fprintf(out,"1");
else if(p==1) fprintf(out,"5");
else if(p==2) fprintf(out,"10");
else {

while(suma<p)
	{
	a=a+5;
	suma+=cate(a);
	}
}
fprintf(out,"%d",a);
fclose(out);

return 0;
}