[백준] 2004번 : 조합 0의 개수 - C#

https://www.acmicpc.net/problem/2004

using System;

class Program
{
    static void Main() {
        string[] s=Console.ReadLine().Split(' ');
        long n=int.Parse(s[0]);
        long m=int.Parse(s[1]);
        long count2=0;
        long count5=0;
        for(long i=2;i<=n;i*=2) count2+=n/i;
        for(long i=2;i<=m;i*=2) count2-=m/i;
        for(long i=2;i<=n-m;i*=2) count2-=(n-m)/i;
        
        for(long i=5;i<=n;i*=5) count5+=n/i;
        for(long i=5;i<=m;i*=5) count5-=m/i;
        for(long i=5;i<=n-m;i*=5) count5-=(n-m)/i;
        
        Console.Write("{0}",count2<=count5 ? count2 : count5);
        
    }
}