#include<cstdio>
using namespace std;
FILE *f,*g;
int n,x,p,nr,k,y;
int main()
{f=fopen("factorial.in","r");
g=fopen("factorial.out","w");
fscanf(f,"%d",&p);
if(p==0)
	fprintf(g,"1");
else
{k=5*p+5;
for(n=4*p;n<=k;n=n+5)
{x=n;
nr=0;
while(x!=0)
{x=x/5;
nr=nr+x;
}
if(nr==p)
{y=n%5;
n=n-y;
fprintf(g,"%d",n);
break;
}}}
fclose(f);
fclose(g);
return 0;
}