C++ :

#include"iostream"
using namespace std;
int main(){
  int s,i,x,y;
  while(cin>>i)
  {x=i;
   s=1;
   for(i=1;i<=x;i++){
     s=s*i;
	if(s%10==0)s=s/10;
     if(s/10000!=0)s=s%10000;
    
   }
   for(;s%10==0;)s=s/10;
   y=s%10;
   cout<<y<<endl;
  }
return 0;
}

Python :

def factorial(n):
    result=n
    for i in range(1,n):
        result *=i
    return result
x=input()
while int(x)<=4220:
    y=factorial(int(x))
    z=list(reversed(list(str(y))))
    for i in z:
            if(i=='0'):
                continue
            else:
                print(i)
                break
    x=input()