백준 1676 팩토리얼 0의 개수 / java

import java.io.IOException;
import java.math.BigInteger;
import java.util.*;
public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		
		int count = 0;
		String resultStr;
		test t = new test();
		resultStr = t.factorial(n).toString();
		for(int i = resultStr.length()-1; i > 0; i--) {
			if(resultStr.charAt(i) == '0') count++;
			else break;
		}
		System.out.println(count);
	}	
}

class test {
	public BigInteger factorial(int num) {
		BigInteger result = new BigInteger("1");
		
		for(int i = 1 ; i <= num; i++) {
			result = result.multiply(BigInteger.valueOf(i));
		}
		return result;
	}
}