我想问问为什么这段代码运行以后始终不能执行fuction2方法

package exercise.example;
import java.io.*;
import java.util.*;

public class P8939 {
    public static void main(String[] args) throws IOException {
        Scanner inp=new Scanner(System.in);
        int n=inp.nextInt(),q=inp.nextInt();
        ArrayList<Integer> a=new ArrayList<>();
        for (int i=0;i<n;i++)
            a.add(inp.nextInt());
        System.out.println();
        for(int i=0;i<q;i++){
            int operation = inp.nextInt();
            if(operation == 1)
                function1(inp.nextInt(), a);
            else if(operation == 2)
                function2(inp.nextInt(), a);
        }
        System.exit(0);
    }
    public static void function1(int m,ArrayList<Integer> a){
        if(!a.contains(m))
            System.out.println(-1);
        else {
            a.remove((Integer) m);
            ArrayList<Integer> b=new ArrayList<>();
            ArrayList<Integer> c=new ArrayList<>();
            b=permutationFunc(a,c,0);
            b.sort(Comparator.naturalOrder());
            System.out.println(b.get(0));
        }
    }
    public static void function2(int m,ArrayList<Integer> a){
        a.add(m);
        ArrayList<Integer> b=new ArrayList<>();
        ArrayList<Integer> c=new ArrayList<>();
        b=permutationFunc(a,c,0);
        b.sort(Comparator.naturalOrder());
        System.out.println(b.get(0));
    }
    public static int sigmaResult(ArrayList<Integer> a){
        int result=Math.abs(a.get(0)-a.get(a.size()-1));
        for(int i=a.size()-1;i>=1;i--)
            result+=Math.abs(a.get(i)-a.get(i-1));
        return result;
    }
    public static ArrayList<Integer> permutationFunc(ArrayList<Integer> list,ArrayList<Integer> b,int start)
    {
        if(start==list.size()-1) {
            b.add(sigmaResult(list));
        }
        for(int i=start;i<=list.size()-1;i++)
        {
            Swap(list,i,start);
            permutationFunc(list,b,start+1);
            Swap(list,i,start);
        }
        return b;
    }
    public static void Swap(ArrayList<Integer> list,int i,int j) {
        int temp;
        temp = list.get(i);
        list.set(i, list.get(j));
        list.set(j, temp);
    }
}