import java.util.Scanner;



	public class Main {



	 public static void main(String [] args)



	 {



	  Scanner sc = new Scanner(System.in);



	  String s = sc.next();



	  



	  System.out.println(back(s));



	  sc.close();



	 }



	 



	 public static int back(String s)



	 {



	  



	  char c1[] = s.toCharArray();



	  char c2[] = new char[c1.length];



	  



	  int d[][]=new int[c1.length+1][c1.length+1];



	  



	  for(int i=c1.length-1;i>=0;i--)



	  {



	   c2[c1.length-i-1]=c1[i];



	  }



	  



	  for(int i=0;i<c1.length;i++)



	   d[i][c1.length-1]=0;



	  for(int i=0;i<c1.length;i++)



	   d[c1.length-1][i]=0;



	  



	  for(int i=1;i<=c1.length;i++)



	  {



	   for(int j=1;j<=c1.length;j++)



	   {



	    if(c1[i-1]==c2[j-1])



	    {



	     d[i][j]=d[i-1][j-1]+1;



	    }



	    else



	    {



	     d[i][j]=Math.max(d[i-1][j],d[i][j-1]);



	    }



	   }



	  }



	  return c1.length-d[c1.length][c1.length];



	 }



	}

其中一组case返回结果为null。。。求教各位大神这个代码有啥问题没