#include<iostream.h>
#include<fstream.h>
fstream in ("cifra.in",ios::in), out("cifra.out",ios::out);
int cifra(long n)
{ long i,j,x,s=0;
for(i=1;i<=n;i++){
	x=1;
	for(j=1;j<=i;j++)
		x=(x%10)*(i%10);
	s=s%10+x%10;
		}
return s%10;
}
main(){
long int n;
while (! in.eof()){
	in>>n;
	cout<<cifra(n)<<endl;
	}
}