import java.math.BigInteger;
import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNextInt()) {
            int n = in.nextInt();
            BigInteger fact = BigInteger.ONE;
            for (int i = 2; i <= n; i++) {
                fact = fact.multiply(BigInteger.valueOf(i));
            }
 
            String factStr = fact.toString();
            int count = 0;
            for (char c : factStr.toCharArray()) {
                if (c == '0') count++;
            }
 
            System.out.println(count);
        }
    }
}
 

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Nw==

7