我感觉我的代码没问题啊，为什么报错RE呢？

import java.io.*;

public class Main{
    static int count = Integer.MAX_VALUE;
    static StringBuilder str = new StringBuilder();
    static BufferedReader ins = new BufferedReader(new InputStreamReader(System.in));
    static StreamTokenizer in = new StreamTokenizer(ins);
    static PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));

    public static void main(String[] args) throws IOException{
        int cl = 0;
        in.nextToken();
        int n = (int)in.nval;
        in.nextToken();
        int m = (int)in.nval;
        String[] strings = new String[n];
        for(int i = 0;i<strings.length;i++)
        {
            strings[i] = ins.readLine();
        }
        for(int i = 1;i<=strings.length-2;i++)
        {
            for(int i2 = i+1;i2<=strings.length-1;i2++)
            {

                for(int i4 = 0;i4<i;i4++)
                {
                    for(int t1 = 0;t1<m;t1++)
                    {
                        if(strings[i4].charAt(t1) != 'W')
                        {
                            cl++;
                        }
                    }
                }
                for(int i5 = i;i5<i2;i5++)
                {
                    for(int t1 = 0;t1<m;t1++)
                    {
                        if(strings[i5].charAt(t1) != 'B')
                        {
                            cl++;
                        }
                    }
                }
                for(int i6 = i2;i6<n;i6++)
                {
                    for(int t1 = 0;t1<m;t1++)
                    {
                        if(strings[i6].charAt(t1) != 'R')
                        {
                            cl++;
                        }
                    }
                }
                count = Math.min(cl, count);
                cl = 0;
            }
        }
        out.print(count);
        out.close();
    }
}