题解 | #末尾0的个数#

import java.util.*;
public class Main {
    public static int solve(int n) {
        int cnt = 0;
        for(int i = 5; i <= n; i += 5) {
            int t = i / 5;
            cnt++;
            while(t > 0 && t % 5 == 0) {
                t /= 5;
                cnt++;
            }
        }
        return cnt;
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(solve(n));
    }
}