完美走位

using System;
using System.Collections.Generic;

class PerfectWalk
{
    public static int MinReplaceLength(string s)
    {
        int n = s.Length;
        int[] count = new int[4]; // 分别记录 A, S, D, W 的步数

        // 统计每个方向的步数
        foreach (char c in s)
        {
            switch (c)
            {
                case 'A': count[0]++; break;
                case 'S': count[1]++; break;
                case 'D': count[2]++; break;
                case 'W': count[3]++; break;
            }
        }

        // 如果已经是完美走位，返回 0
        if (count[0] == count[1] && count[1] == count[2] && count[2] == count[3])
        {
            return 0;
        }

        // 滑动窗口
        int left = 0;
        int minLen = n;
        for (int right = 0; right < n; right++)
        {
            // 更新当前窗口内的步数
            switch (s[right])
            {
                case 'A': count[0]--; break;
                case 'S': count[1]--; break;
                case 'D': count[2]--; break;
                case 'W': count[3]--; break;
            }

            // 检查当前窗口是否满足条件
            while (IsPerfect(count))
            {
                minLen = Math.Min(minLen, right - left + 1);
                // 移动左指针
                switch (s[left])
                {
                    case 'A': count[0]++; break;
                    case 'S': count[1]++; break;
                    case 'D': count[2]++; break;
                    case 'W': count[3]++; break;
                }
                left++;
            }
        }

        return minLen;
    }

    private static bool IsPerfect(int[] count)
    {
        return count[0] == count[1] && count[1] == count[2] && count[2] == count[3];
    }

    public static void Main(string[] args)
    {
        string s = Console.ReadLine();
        int result = MinReplaceLength(s);
        Console.WriteLine(result);
    }
}